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THE REFEACTION OF THE EYE 



j3^^ 



THE REFRACTION OF THE EYE 

INCLUDING A COMPLETE 

TREATISE ON OPHTHALMOMETRY 



A CLINICAL TEXT-BOOK FOE STUDENTS AND 
PRACTITIONERS 



BY 



A. EDWARD DAVIS, A.M., M.D. 

Adjunct Professor of Diseases of the Eye in the New York Post-Graduate 

Medical School and Hospital; Assistant Surgeon to the Manhattan 

Eye and Ear Hospital ; Attending Ophthalmic Surgeon to the 

Babies' Waixls of the New York Post-Graduate Hospital ; 

Attending Ophthalmic Surgeon to Bellevue Hospital, 

Out-door Department ; Secretary of the Neio York 

Ophthahnological Society ; Assistant Secretary 

of the Neiu York Physicians' Mutual Aid 

Association ; 

Member of New York State Medical Society, County Medical Society, 

Academy of Medicine, etc. 



WITH ONE HUNDRED AND NINETEEN ENGRAVINGS 

NINETY-SEVEN OF WHICH ARE ORIGINAL 



THE MACMILLAN COMPANY 

LONDON: MACMILLAN & CO., Ltd. 
1900 

All rights reserved 



TWO COPIES aECElVEU. 

""'OS Of tua 
«»8l«t«r of Copyrights 










51342 



Copyright, 1900, 
By the MACMILLAX COMPANY. 



SECOND COPY, 






'^c^^.^.\c^^ 



XortoootJ ^ress 

J. S. Cushing & Co. - Berwick & Smith. 
Norwood Mass. U.S.A. 



TO 

PS M^n 
H. C. DAVIS, M.D. 

AND 

fHg EUn 23rrrtfjer 
GEORGE E. DAVIS, M.D. 

THIS VOLUME 
IS AFFECTIONATELY DEDICATEI> 



PEEFACE 

Since the introduction of the perfected ophthalmometer 
into ophthalmic practice, rapid strides forward in the art of the 
refraction of the eye have been made. With its aid, the prac- 
tice of fitting glasses quickly and accurately and, as a rule, 
without the aid of any mydriatic whatever has been attained. 
It is to the end of demonstrating the clinical and practical 
use of the ophthalmometer, and of recording the advances 
made in the science and practice of the Refraction of the Eye, 
that this book has been written. Some half dozen books on 
Ophthalmoscopy and Retinoscopy have been written, and the 
time is opportune for one on Ophthalmometry. We have one 
such book in French, Javal's Memoires d' Ophtalmometrie, but 
none in English. 

While the present book is intended more especially for 
beginners, and for those who have not had the advantage of 
personal instruction in the use of the ophthalmometer, it is 
hoped that its clinical details will interest those in active 
practice, and who are well versed in the use of the instrument 
of which it treats. I am especially desirous that it shall be 
read by a certain rather considerable number of oculists who 
have the ophthalmometer in their offices, but who, from the 
want of a proper understanding of it, through faulty instruc- 
tion or a lack of personal instruction, do not use it ; or, if they. 
do know how to use it, do not take into consideration the 
limitations of the instrument, and abandon it on tliat account. 
Through the citation of a great number of clinical cases, 
together with numerous diagrams illustrating them, I have 



viii PREFACE 

tried to show tlie virtues of the ophthalmometer, while I have 
not omitted to note its limitations. In that way, I have hoped 
to present the instrument in the true light and to justify the 
claims made for it. 

In composing the book, I have departed from the beaten 
path, and have devoted the greater part of it to the report 
in detail of clinical cases illustrating practical points in the use 
of the ophthalmometer. In other words, instead of a theoreti- 
cal and didactical discburse, I place a sufficient number of 
cases themselves (one hundred and fifty in all) before the eye 
of the reader, which are reported in full, so as to be easily 
understood. To be more explicit still, I may say I have made 
my teaching correspond, so far as it is possible in a book, to the 
instruction that we give at the Post-Graduate Medical School, 
where the instruction is entirely clinical. 

I have given an Index of Cases at the close of the book, 
so that the reader who has a case that he does not fully under- 
stand, may turn to this index and look for cases in it similar to 
his, and then refer to the full report in the body of the book. 
By comparison he may get a solution of the case that is puz- 
zling him. I have done this in order that the student may 
not be '' lost with a case," as is too often true when he refers 
to the larger text-books wherein no such index is given. It 
has been my experience that more can be taught the student 
by one concrete case illustrating a point in question, than by 
many pages of abstract deduction concerning cases which have 
never been presented to the student himself. 

After giving a brief description of the instrument and the 
rules for its use, with some general considerations, I have treated 
successively, in separate chapters, of its practical use in cases of 
Simple Hypermetropia and Hj'permetropic Astigmatism, Com- 
pound Hypermetropic Astigmatism, Simple Myopia and Myopic 
Astigmatism, Compound Myopic Astigmatism, and Mixed As- 
tigmatism, giving many cases and using diagrams to show the 



PREFACE ix 

point of focus of the principal meridians, so that the merest 
tyro must understand them. Incidentally throughout the 
book, I have endeavored to show the utter uselessness of a 
mydriatic in fitting glasses in the vast majority of cases, even 
in young subjects. If the Ophthalmometer is correctly used 
and a good routine method followed in putting the glasses in 
the trial frames in the subjective test, as here suggested and 
fully explained, the use of a mydriatic is, with rare exceptions, 
never necessary in order to give the right glasses. 

I desire to express my sincere thanks to Professor St. John 
Roosa for his kindness in looking over the manuscript, and for 
many valuable suggestions both as to the matter and the form 
of the composition. 

Mr. Fred Stuart has given me much assistance in proof- 
reading, which I here acknowledge with thanks. 

Mr. Norman P. Findley has made the original drawings 
for the book. For the cuts of instruments I am indebted to 
JVIr. E. B. Meyrowitz and the publishers of the book. 

A. EDWAED DAVIS. 

New York, December, 1899. 



CONTENTS 

CHAPTER I 

PAGH 

History of the Ophthalmometer — Description of the Instrument . 1 

CHAPTER n 

Principle of the Application of the Ophthalmometer in measuring 
Astigmatism — Rules for its Use — Astigmatism "with the Rule" 

— Astigmatism "against the Rule" — Why the Mires overlap in 
Astigmatism with the Rule and separate in Astigmatism against 
the Rule — Why we deduct half a Diopter from the Reading of 
the Instrument in Astigmatism with the Rule and add a half 
Diopter to the Reading when it is against the Rule — Rule of 
Procedure when the Main Meridians are at 45° and 135° — Prin- 
ciple of the Application of the Ophthalmometer . . . . 13 

CHAPTER III 

General Considerations in the Use of the Ophthalmometer — Simple 
Hypermetropic Astigmatism — Simple Hypermetropia — Illustra- 
tive Cases 36 

CHAPTER IV 

Compound Hypermetropic Astigmatism — Illustrative Cases — Spasm 

of Accomrpodation .80 

CHAPTER V 

Simple Myopic Astigmatism — Myopia — Spasmodic or False Myopia 

— Rule for prescribing Near or Reading Glasses in High Degrees 
of Myopia — Presbyopia and the Transposition of Glasses from 
Distance to Reading in Myopes when it is Present » . .122 

xi 



xii CONTEXTS 

CHAPTER YI 

PAGB 

Compound Myopic Astigmatism — Antimetropia — Illustrative Cases 

— Accessory Effects of Strong Myopic Glasses .... 147 

CHAPTER Vn 
Mixed Astigmatism — Illustrative Cases 175 

CHAPTER YIII 

Irregular Astigmatism — Conical Cornea — Hyperbolic Lenses — Con- 
tact Lenses — Illustrative Cases , . 209 

CHAPTER IX 

Strabismus — Insufficiencies of the Recti Muscles — Amblyopia — Illus- 
trative Cases 235 

CHAPTER X 

Astigmatism after Cataract Extraction — Toric Lenses — Periscopic 

Lenses — Decentering of Lenses — Illustrative Cases » . . 309 

CHAPTER XI 

Exceptional Cases — Variations in the Amount and Axis of the Astig- 
matism as shown by the Ophthalmometer and as Indicated by the 
Glasses Accepted by the Patient — Illustrative Cases , , . 318 

APPENDIX 

Improvements on the Javal-Schiotz Ophthalmometer: (a) Davis's 
Double-movable Mires ; (b) Talk's Gear-wheel Attachment ; 
(c) Skeel's Perpendicular Lever Adjustment ; (d) Metal Base 
and other Minor Improvements — Reid's Ophthalmometer, a 
Description of it and how to use the Instrument — Other Oph- 
thalmometers ... 383 

Index of Cases 411 

General Index 427 



THE KEFEACTION • OF THE EYE 






CHAPTER I 

HISTORY OF THE OPHTHALMOMETER — DESCRIPTION OF THE 

INSTRUMENT 

History of the ophthalmometer. - — The ophthalmometer is 
an instrument designed to measure the radius of curvature 
of the cornea in its various meridians. By its use the presence 
or absence of corneal astigmatism is ascertained; if present, 
it gives the amount and the axis of the astigmatism. 

The instrument was invented by Helmholtz who, as early as 
185-i, published a description of it together with his conclu- 
sions as to the exact form of the cornea, as measured by the 
instrument.^ Although very accurate in its measurements, 
the instrument, as constructed by Helmholtz, was not a prac- 
tical one. In order to use it the patient was placed six feet in 
front of it, and from fifteen to twenty readings made ; then, 
before the astigmatism was ascertained, mathematical calcula- 
tions had to be made. As such, it was used in the laboratories 
of only a few men and for strictly scientific purposes. 

It was not until 1880, when Javal and Schiotz made altera- 
tions and improvements in the instrument, that it became 
practical for office use, and it was not until 1889 that they 
perfected the instrument into its present model. As now 
constructed, it has about reached the limit of improvement, 
except as to minor details ; consequently the purchaser is safe 
in buying it and with the assurance that it will not soon be a 
back number. 

Dr. Swan M. Burnett, of Washington, was the first Ameri- 

1 "Ueber die Accommodation des Auges," Arch iv fur Ophthalmol, 18-54. 

1 



2 THE REFRACTION OF THE EYE 

can to use the Javal ophthalmometer. As earl}^ as 1885 he 
published a paper in the Archives of Ophthalmology^ Vol. XIV, 




Fig. 1. — The ophthalmometer complete. 

under the title of '' Ophthalmometry with the Ophthalmometer 
of Javal and Schiotz, with an Account of a Case of Keratoco- 



DESCRIPTION OF THE OPHTHALMOMETER 3 

nns." Dr. Henry D. Noyes, of New York, began using the 
instrument about the same time. Both of these instruments 
were old models. In 1887, Dr. Burnett gave a description of 
the old model instrument in his Treatise on Astigmatism ; and 
in the same year, 1887, in the Reference Hand Booh of the 
Medical Sciences^ Dr. John Green, of St. Louis, gave a descrip- 
tion of the instrument with a cut. The instrument remained 
comparatively unknown, however, in this country until 1889. 

When the new or " 1889 model " came out it found among 
its advocates, among others. Dr. D. B. St. John Roosa, of New 
York, who by his earnest and persistent advocacy of the instru- 
ment, especially in the class-room and in the hospital, where 
practical demonstrations of its use and value were given, did 
much to bring it into general favor. Other writers in America 
who have helped to bring the ophthalmometer into esteem are : 
Speakman, KoUer, Ring, Weiland, Van Fleet, Wurdeman, 
Swasey, Woodward, Valk, De Schweinitz, Norris, myself, and 
others. 

Construction of the instrument. — To be able to use the 
ophthalmometer well the oculist should at least be somewhat 
familiar with its construction. 

The instrument is composed of the following parts : — 

1. A telescope on an upright, supported by a tripod. 

2. A graduated arc, which is the quarter of a circle and 
attached to the telescope at right angles to it. 

3. Two mires or reflectors which are attached to the gradu- 
ated arc. 

4. A large steel disk (Placido's) attached to the telescope, 
just back of the graduated arc. 

5. The planchette or base for the instrument to rest on. 
The telescope, — The telescope is made of brass and has a 

fixed length. It contains : (a) an ocular or eye-piece (0, Fig. 
2, J.) of .7 inch focus or 56 diopter power ; (?>) double objectives 
(L and L', Fig. 2, A) of 11.2 inch focus each, or about 4 diopter 



4 THE REFRACTION OF THE EYE 

power ; (c) a cross-thread to show when the eye-piece and 
objectives are in adjustment ; (c[) and a double refracting 
Wallaston prism (W^ Fig. 2, A). 

(a) The eye-piece can be made to approach or to recede 
from the objectives by means of a small pin which is fixed on 
the side of the brass ring that holds the eye-piece, sliding in an 
oblique groove in the side of the telescope. When the cross- 
threads in the barrel of the telescope are brought into view by 
this means, it shows that the eye-piece is in proper focus with the 





Fig. 2. — A, showing vertical sections of the telescope and its component parts. 
B, horizontal section of the telescope. 



proximal objective (X', Fig. 2, A) ; and when the distal objective 
(i. Fig. 2 ^,) is brought into exact focus with the eye observed, 
a perfect image of the mires is possible. If the observer is 
myopic, he has to push the eye-jDiece inward or to the right to 
get the cross-threads in focus ; if he is hypermetropic, the eye- 
piece has to be pulled outward or to the left to properly focus 
them. The eye-piece should always be properly adjusted for 
the cross-threads before focussing the instrument on the ob- 
served eye. The imported instruments, made by Goubeaux, of 
Paris, have graduations along the oblique slit in which the pin 
on the eye-piece slides. These graduations are so placed that 



DESCEIPTIOi^ OF THE OPHTHALMOMETER 5 

each corresponds to a displacement of the eye-piece to the 
extent of 1 mm., each millimeter of displacement corresponding 
to a change in the observer's eye of 3 diopters. For example, 
when the pin on the eye-piece stands at zero an emmetropic 
observer should see the cross-threads in the telescope plainly, 
while a myope of 3 diopters would have to turn the pin one 
graduation to the right, and a hypermetrope of 3 diopters 
would have to turn the pin one graduation to the left in order 
to see the cross-threads distinctly. 

(5) The two objectives are exactly alike. Each has a 
diameter of 40 mm., or 1.6 inches, and a focal distance of 280 
mm., or 11.2 inches. They are the most perfect lenses made, 
being both achromatic and aplanatic. 

They are so placed in the barrel of the telescope that the 
crown of one is turned toward the observed eye, and the crown 
of the other toward the observer. By this means the flints of 
the two objectives are kept opposed and next to the bi-refract- 
ing prism. 

(a) The cross-threads are two very fine wires stretched at 
right angles to each other across the barrel of the telescope 
about 1 inch in front of the eye-piece and about 11.2 inches 
behind the first objective, L' . They are there simply to show 
when the eye-piece is in proper focus with the objectives. 

(d) The hi-refracting prism (Wallaston) placed between the 
two objectives is in fact two prisms, placed apex to base and 
base to apex. In this country, at least in the instruments man- 
ufactured by Meyrowitz and Georgen, these prisms are made 
from the best mountain crystal quartz. They possess the power 
of doubling objects, that is, are bi-refractive, if ground in a 
certain direction with regard to the axis of the quartz. The 
amount of the deviation or doubling produced by each prism 
depends on the angle at which it is ground. 

One of the prisms is ground diagonally with the grain of 
the quartz (a. Fig. 3), while the other is ground at right angles 



THE REFRACTIOX OF THE EYE 




Fig. 3. — Thebi-re- 



to it («', Fig. 3); see cut, looking down on them from above as 
they are placed in the telescope of the instrument. Thus placed, 
their axes are at right angles to each other and at the same time 
transverse to the axis of the telescope. Each 
prism when ground at a certain angle causes a 
definite amount of deviation; and by using two 
prisms, apex to base and base to apex, the de- 
viation takes place from each side, thus getting 
twofold the deviation that would be caused by 
one prism and at the same time keeping the 
doubled images nearer the center of the field. 
Furthermore, these prisms are placed in the 
fractive prism telescope with their plane of doubling in ex- 

as placed in the , . 

telescope. ^^^ ^^^^® With the plane ot the graduated arc, 

which latter is fixed to the telescope of the 
instrument at right angles to it by two screws in a brass 
collar. 

It is very important, therefore, that these two screws should 
not be meddled with; for, if moved in the least, the arc and 
the plane of the prism is altered, and the instrument cannot be 
used again until readjusted by an expert. 

The prisms in Javal's instrument produce a deviation of 2.95 
mm. when the instrument is focussed on an object at double the 
focal distance of the objective, or 460 mm. When, therefore, 
the instrument is properly focussed on the cornea, the latter is 
doubled by the prism, and each point of the image reflected 
from the cornea is displaced to the extent of 2.95 mm. Con- 
sequentlj^ if the image of the object reflected from the cornea 
happened to be just 2.95 mm. in length, the de^dation of 2.95 
mm. caused by the prism would allow the edges of the doubled 
image to just touch, as in Fig. 4. 

Say the image of the arrow 1-2 is just 2.95 mm. in length, 
and by the deviation caused by the prism each of its points are 
displaced correspondingly the distance of 2.95 mm. ; then the 



DESCRIPTION OF THE OPHTHALMOMETER 7 

tail of the secondary image, V-2', will just touch the head of 
the primary image, 1-2. 

In this way we are enabled to measure the size of the cor- 
neal image by the amount of displacement it is necessary to 



2.95 MM. , 2.95 MM 




1 2 1 2 

Fig. 4. — Showing the exteut of displacement in the Javal-Schiutz instrument. 

give to each point of the image in order to have the edges 
of the doubled images just touch. 

Instead of an arrow, Javal takes for his object the distance 
between the inner edges of two mires or reflectors, 1 and 2, 
Fig. 7. Here, as in the case of the arrow, the prism, from its 
fixed position in the telescope, causes a deviation of 2.95 mm. 
Consequently, if the two mires are so arranged on the arc of 
the instrument that, by this deviation of 2.95 mm., the inner 
edges of the images of the two mires are just touching, it is 
quite plain that the diameter of this image must be just 2.95 mm. 
Furthermore, it is equally plain that the distance between the 
inner edges of the two mires, in this instance, is equal to the 
size of the object, in fact, is the object which gives a reflected 
image 2.95 mm. in diameter. 

The bi-refracting prism in the Javal-Schiotz instrument 
causes a fixed deviation of 2.95 mm.,^ the arc on which the 
mires move has graduations to show the distance apart of 
the two mires, and thereby the size of the object; and twice the 
focal distance of the objective determines the distance of the 
object from the cornea. With these three points known it is 
easy to find the fourth, the radius of curvature of the cornea 

1 An extra tube with a prism causins; less deviation and therefore a smaller 
image is furnished with the instrument which is of use in cases of marked varia- 
tion from the average radius of curvature of the cornea. 



I 



I 



8 THE REFRACTION OF THE EYE 

in its various meridians, and thereby ascertain the presence or 
absence of astigmatism — the object of the ophthalmometer. 

The graduated arc is an arc with a radius of its inner edge 
of 290 mm. When focussed on the observed eye it is concentric 
with the cornea. The posterior edge of the arc is graduated 
into equal spaces and numbered, the numbering beginning at 
the center and extending in each direction to 40 spaces. Each 
one of the divisions on the posterior edge of the arc, taken in 
connection with the doubling of the image by the prism, stands 
for a diopter mark. For example, if, with an eye under observa- 
tion and the arc in the horizontal meridian, the images of the 
mires just touch when the mires on each side of the arc stand 
at the 20 mark, it shows that the refractive power of the hori- 
zontal meridian of the cornea is 40 diopters. If now we turn 
the arc to the vertical meridian of the cornea and the images of 
the mires overlap, say three steps, it shows 3 diopters of astig- 
matism, which may be verified by the graduations on the poste- 
rior edge of the arc in the following way. While still looking 
at the images through the telescope as they appear overlapped 
there, move the graduated mire outward along the arc till the 
images are left just touching again. Then by looking at the 
posterior edge of the arc we will find that the graduated mire 
has moved the distance of just three graduations ; thus veri- 
fying the amount of astigmatism present and at the same time 
showing the vertical meridian of the cornea to have a refractive 
power of 43 diopters. 

On the right side of the arc on its inner edge are some 
fine graduations and some figures. On the instrument 
with the single movable mire these figures go from 6 mm. 
to 10 mm. ; on the instruments with double movable mires 
(improved) from 5 mm. to 13 mm. By noting the position 
of the graduated mire on the right side of the arc in relation 
to these graduations when the images of the two reflectors just 
touch, in any meridian whatever, the number corresponding 



DESCRIPTION OF THE OPHTHALMOMETER 9 

indicates the radius of curvature of the cornea in that particu- 
lar meridian in millimeters. These figures are very important, 
therefore, and should be noted carefully, for by them we are able 
to register the radius of curvature of the cornea in millimeters 
in its various meridians. 

Two mires or reflectors are attached to the arc. One of 
them is a parallelogram, 60 mm. long by 30 mm. wide, and, in 
the unimproved instrument, is fixed at 20 on the left-hand side 
of the arc. The other is a graduated mire, each graduation or 
step is 10 mm. long by 5 mm. broad, and counts as 1 diopter. 
There are eight of these steps. 

Dividing the mires into halves are two narrow black lines, 
called guide-lines. The lines are parallel with the planes of 
the arc. They serve to show when the arc is in one of the 
chief meridians of curvature of the cornea, that is, when it 
is in the meridian of longest radius of curvature, or in the 
meridian of the shortest radius of curvature. 
They do this by showing perfectly straight and 
opposite each other when the arc is turned to 
either of the chief meridians of curvature (see 
Fig. 5), but run obliquely toward each other in 
all other meridians (see Fig. 6). Of course where there is no 
corneal astigmatism, the cornea being uniformly and evenl}^ 
curved, they will remain straight and opposite 
each other in all meridians. As we have to find 
one of the chief meridians of the cornea, that 
is, get the "primary position" or starting point ^ . 

in measuring corneal astigmatism, these lines are 
of much importance. A small pointer or indicator is attached 
to the outer side of each mire, which points to figures on the 
periphery of a large disk, where the axis of the meridian is 
marked in degrees of a circle. These short indicators on the 
reflectors serve as a check to a long indicator which is attached 
to the middle of the graduated arc and at right angles to it. 




Fig. 5. 




10 THE REFRACTION OF THE EYE 

This long indicator shows the direction the arc is in when the 
long black lines dividing the reflectors become straight with 
each other. For example, say the black lines dividing the mires 
become straight when the arc is in the horizontal meridian of a 
cornea having astigmatism with the rule. The long indicator, 
since it is at right angles to the arc, wdll be pointing directly 
downward (directly upward, however, as seen in the telescope, 
because the image is an inverted one) to 0°, which is the same 
as regards axis as 180°, for 180° just completes the half of a 
circle. 

It will be noticed that 0° or 180° is marked on the big disk 
directly above and directly below, and does not occupy the 
horizontal meridian, as is usually the case. This is due to the 
fact that the long indicator is at right angles to the arc whose 
direction it indicates. Therefore, when the arc is really in the 
horizontal meridian (0° or 180°) the long indicator is in the 
vertical meridian, consequently the 0° has to be put there. 
This explains why 0° is marked in the vertical meridian and 
90° in the horizontal meridian on the disk. 

When the long indicator points to 0° the short indicator 
should point exactly to 90° ; in this way the latter serves as 
a check to the long indicator, as above stated. 

The disk (Placido's) is a large circular sheet of steel 640 
mm. (25.6 inches) in diameter attached to the telescope at 
right angles to it and just back of the graduated arc. Upon 
this disk are concentric white circles on a black background, 
also radiating lines extending from its center. The concentric 
white circles are five degrees apart, numbering from the center 
to the periphery a distance of 45°. They are constructed on 
the law of tangents, that is, the radius of each circle represents 
the tangent of an arc drawn from the center of the graduated 
arc. 

The circles marked 15° and 30° are broader than the others, 
and on the 30° circle beginning above, the radiating lines from 



descriptio:n^ of the ophthalmometer 11 

the center of the disk are numbered in the degrees of a circle 
from 0° to 360° — a complete circle (see Fig. 1). By number- 
ing both the concentric circles and the radiating lin-es in this 
manner, this disk can be used as a perimeter ; for the same 
reason it can be used to make observations on the cornea out- 
side of the visual line. 

At the periphery of the disk, between the 40° and the 45° 
circles, is a large white border. On this white border are 
large inverted figures 15° apart. Instead of numbering 
from 0° to 360°, as did the small figures on the 30° circle, 
they stop at 180°, then begin again and number up to 180° 
or 0°, where they first began (see Fig. 1). These figures 
appear upright or straight when viewed as a reflected image 
from the cornea, for this image is inverted. 

On the right side of the disk in the horizontal meridian the 
numbers 3 mm., 4 mm., and 5 mm. appear. These are meant 
to aid in measuring the diameter of the pupil. In order to do 
so, however, an extra strong objective has to be put in the 
telescope, and an extra brilliant illumination obtained. If the 
pupil seems to extend out to the circle marked 3 mm., it is 
3 mm. wide, etc. 

On the opposite side of the disk are seen the figures 35, 40, 
45, and 50. When viewed in the corneal image, if any one 
of these circles so numbered become tangent to itself (through 
the doubling caused by the prism), the figures denote the powder 
of refraction, or dioptric power, of the cornea in that meridian. 
For example, say the circle marked 40 becomes tangent to 
itself — thus 00 — in the horizontal meridian ; the refractive 
power of the cornea in that meridian would be 40 diopters. 

The reason that the numbering at the periphery of the disk 
begins at 0° and goes to 180°, then repeats itself from 0° to 
180° again instead of completing the circle of 360° (as in the 
30° circle in small figures), is that both ends of any corneal 
meridian under measurement may be indicated by the same 



12 THE REFRACTION OF THE EYE 

number on each side of tlie disk. For this reason each mire 
has a short pointer on it. These pointers not only point to 
the same number of degrees on each side of the disk, but serve 
as a check at the same time on the long pointer or indicator. 
For example, when the short pointers each point to 0°, the long 
pointer should be exactly at 90°, at right angles. Again, by 
means of these short pointers and the double numbers on the 
disk, the angles of the chief meridians can be seen at once from 
the reflected image. This is one strong reason why this big 
disk should not be removed from the instrument and replaced 
by a smaller black velvet disk and upright numbering on a 
small medal disk facing the observer, as is now sometimes done 
by some Americans. 

For a description of the improvements made on the Javal- 
Schiotz instrument and modifications of it, and for descriptions 
of other ophthalmometers, see Appendix. 



CHAPTER II 

PRINCIPLE OF THE APPLICATION OF THE OPHTHALMOMETER IN 
MEASURING ASTIGMATISM — RULES FOR ITS USE — ASTIGMA- 
TISM "WITH THE RULE"— ASTIGMATISM "AGAINST THE 
RULE"— WHY THE MIRES OVERLAP IN ASTIGMATISM WITH 
THE RULE AND SEPARATE IN ASTIGMATISM AGAINST THE 
RULE — WHY WE DEDUCT HALF A DIOPTER FROM THE READ- 
ING OF THE INSTRUMENT IN ASTIGMATISM WITH THE RULE, 
AND ADD A HALF DIOPTER TO THE READING WHEN IT IS 
AGAINST THE RULE — RULE OF PROCEDURE WHEN THE MAIN 
MERIDIANS ARE AT 45° AND 135° — PRINCIPLE OF THE APPLI- 
CATION OF THE OPHTHALMOMETER 

The principle on which the ophthalmometer acts in meas- 
uring the radius of curvature of the cornea in its various 
meridians, and thereby marking the corneal astigmatism, con- 
sists simply in the measurement of the size of a small image 
reflected on the cornea. 

In order to measure this image the more easily, it is first 
doubled by the bi-refracting prism in the telescope of the 
instrument. The objects furnishing this image are the inner 
edges of the two mires. The images of both the mires, as 
well as that of the disk, are doubled by the prism, so that, as 
viewed through the telescope, we have four mires and two 
disks (see Fig. 7). 1 and 1' are the images of the graduated 
mire, and 2 and 2' are the images of the rectangular mire. 
In practice, however, we pay no attention to the two outer 
images, 1 and 2,^ but notice simply the two inner images. 1' 
and 2, in the oval space made by the overlapping of the double 
images of the disk (see Fig. 7). The distance, a a', between 
the inner edges of the images of the rectangular mire, denoted 

13 



I 



I 



14 



THE REFRACTION OF THE EYE 



by the dotted line in Fig. 7, and h h\ the distance between the 
inner edges of the images of the graduated mire, each repre- 
sents the amount of deviation caused by the prism, which is 
2.95 mm. Now as a a' is tlie image of the object under meas- 





FiG. 7. 



A, diagram of the mires alone. B, reflection of the whole instrument from 
the front of the cornea, with the arc at 180°. 



urement, that is, the distance between the inner edges of the 
two mires, we know its size to be just 2.95 mm. in this 
instance. Take a case in actual practice. For example, when 
the instrument is focussed properly on an eye, the black lines 
dividing the mires become coincident with each other in the 



USE OF THE OPHTHALMOMETER 



15 



horizontal meridian (c d, Fig. 7). This shows that one of the 
chief meridians of curvature of the cornea is the horizontal 
meridian. Approximate the images till they just touch, then 
turn the arc at right angles to the horizontal meridiaUo If 
there is no overlapping or separation of the images V and 2, it 
shows that the vertical meridian of the cornea has the same 
radius of curvature as the horizontal. If the vertical meridian 




Fig. 8. — The same images as in Fig. 7, but with the arc at 90°. 



has a shorter radius of curvature, the images will overlap to a 
certain extent, say, two steps (see Fig. 8). 

This must necessarily be so, for the size of the ohject (the 
distance between the inner edges of the mires as placed on the 
arc) and the distance of this object from the cornea havino- 
remained the same, we must obtain a smaller image on a sur- 
face with a shorter radius of curvature. The distance between 
1 and 1' and 2 and 2' remaining the same from the constant 
deviation caused by the prism, the reduction in the size of the 



16 THE REFRACTION OF THE EYE 

corneal image cannot take place in a change of length of these 
lines. It must be brought about, therefore, by an overlapping 
of the inner edges of the images 1' and 2 (Fig. 8). The num- 
ber of steps overlapped shows the amount of astigmatism, and 
the direction of the long and short indicators respectively shows 
the axis at which plus or minus glasses will be worn, in any 
case whatever. 

RULES FOR ITS USE 

These rules for the use of the ophthalmometer are taken in 
the main from articles on this subject by myself .^ They are 
intended to be so simple, plain, and direct, that even the very 
beginner should be able to use the instrument by their guid- 
ance. Of course, personal instruction is always preferable to 
written, and, where it is possible, I would advise several les- 
sons by some one skilled in the use of the instrument. 

1. Have a perfect light. The light from a large north 
window ; four 16-candle-power electric lamps ; or two Welsbach 
gas burners with suitable reflectors, are all good illuminants. 

2. See that the telescope, or tube, of the instrument is cor- 
rectly adjusted, by sighting through it, and bring the cross- 
wires in good view. This is done by turning the ocular, or 
eye-piece, to the right when the observer is myopic, and to tlie 
left when he is hypermetropic. The further to the left that the 
eye-piece can be turned, and yet the cross-wires be maintained 
in good view, the better ; and for the same reason which we 
follow in prescribing glasses — the weaker the minus and the 
stronger the plus glass the better, because by this means no 
extra accommodation is called into play. 

3. Place the patient at the instrument with his chin on the 
chin-rest and his forehead against the forehead-rest, with his 
eyes wide open and upon a level. To know when the eyes are 
exactly horizontal, which is all important, sight through the 

1 New York Medical Journal, September 10, 1892, October 8, 1892. 



RULES FOE, ITS USE 17 

transverse slit in the disk just above the tube, or telescope, of 
the instrument. This point cannot be insisted upon too much, 
for the least rotation of the head will throw the axis off 5° or 
10° from what it really is, and then, when we come to the trial 
case, and the axes do not correspond, we are prone to blame the 
instrument when we are ourselves at fault. 

4. The eyes level, we are now ready to place the blind in 
front of one eye and focus the other. To focus the eye, sight 
along the upper side of the tube through the notch (something 
like a gun sight) at the center of the cornea. Now sight 
through the tube, at the same time moving the instrument for- 
ward and backward on the planchette, and u;^ and down by 
means of the screw, until the image of the disk, doubled by the 
prism in the telescope, and reflected from the cornea inverted, 
comes into view. Pay no attention to the two reflectors far out 
at the sides, but notice the two reflectors in the oval space 
made by the overlapping of the disks. 

5. Obtain the "primary position." The " primary position" 
is nothing more or less than that point at which the transverse 
lines, dividing the reflectors into halves, become opposite, or 
coincident, and form one continuous straight line, which is an 
indication simply (when there is any astigmatism) that we have 
found one of the axes of the astigmatism. The other axis, in 
the great majority of cases, is 90° from this, therefore at right 
angles to it, and is the "secondary position." When there is 
no astigmatism, the transverse lines are always opposite and 
coincident. When there is irregular astigmatism, they are 
never coincident. To obtain the primary position, first turn 
the long indicator to 0°. If the transverse lines are coincident 
at this point, go no further ; tliat is the primary position. If 
not coincident at the zero point, turn the tube from right to 
left — that is, the long indicator from 0° to 135°. If the trans- 
verse lines do not become coincident before or when 135° is 
reached, go no farther in that direction, but turn back to 0°, 



18 THE REFRACTION OF THE EYE 

turning this time from left to right, toward 45° ; the lines will, 
necessarily, become coincident before 45° is reached. The 
primary position is never farther than 45° on either side of 0°. 
This I wish especially to emphasize, for if we turn farther than 
the 135° mark on one side or the 45° on the other, we will make 
the astigmatism " with the rule," when it is really " against the 
rule," and vice versa. When the lines become coincident at 
135° or 45°, the extreme limits, being just halfway between 0° 
and 90° on either side, by preference take 135° as the primary 
position — this for the sake of nomenclature. We see then 
that the "■ primary position " may he at 0° or any point within 
45° of that point, but never beyond. Having got the lines 
coincident, it is only necessary to approximate the reflectors to 
be ready for the next step. 

6. That of obtaining the "second position." This is ob- 
tained by turning the long indicator 90° to the left from the 
primary position. If the reflectors overlap, there is astigma- 
tism with the rule, and the number of steps of overlapping is 
the amount of the astigmatism. Say it overlaps two steps. It 
should be written thus : " Astigmatism with the rule, 2 D. 
90° + or 180° — ." If the reflectors separate when the second 
position is reached, it indicates astigmatism against the rule. 
Before moving the indicator from the second position, approxi- 
mate the reflectors again, and then turn back to the primary 
position, when the plates Avill overlap — say two steps, written 
thus : "Astigmatism against the rule, 2 D. 180°+ or 90°-." 
Following the rules above, the long indicator always points the 
axis the plus glass will be worn, and the short indicator on 
the reflectors the axis the minus glass will be w^orn — in any 
case. It may be asked why I prefer to turn the cylinder from 
right to left. Simply that I may have the sliding indicator 
below, where I can get at it through the holes in the disk below. 

Of course the observer's eye should be properly corrected if 
he has any error of refraction. 



ASTIGMATISM WITH THE RULE 19 

Now, what does the instrument do ? It gives the amount 
of the astigmatism and the axis. These points ascertained, 
the rest is easy. 

As to the amount of the astigmatism as indicated by the 
ophthalmometer and that accepted by the patient, we need 
never be in doubt as to the proper glass to prescribe if we will 
only follow what Javal has taught us, that in astigmatism 
"with the rule" — that is, the vertical axis of the cornea being 
the more curved, let the astigmatism be hypermetropic, myopic, 
mixed, simple, or compound — we have only to subtract one- 
half to three-quarters of a diopter from that indicated by the 
instrument to have the proper glass ; and in astigmatism 
*' against the rule," the horizontal meridian of the cornea being 
the more curved, let the astigmatism be hypermetropic, myopic, 
mixed, simple, or compound, to give full correction we add 
half a diopter to that indicated by the instrument. The ex- 
ceptions to this rule are rare, the variation of half a diopter 
too much with, and half a diopter too little against, the rule 
being a fairly constant one and one to be expected, in the 
great majority of cases. Of course the readings of the instru- 
ment should be verified by the ophthalmoscope and trial case 
before glasses are prescribed. 

Astigmatism '■^ with the rule,^' — There has been so much 
confusion in the minds of beginners, and I may say also even 
in the minds of men of considerable experience, about astig- 
matism " with the rule " and astigmatism " against the rule " 
that very explicit and short definitions of each will not be out 
of place here. Where the vertical meridian of the cornea, or any 
meridian in the neighborhood of the vertical meridian, that is, 
within 45° of the vertical, is more curved than the meridian at 
right angles to it, that condition is called astiginatism with 
the rule. 

This is all there is to astigmatism with the rule ; it simply 
means that the vertical meridian of the cornea, or one near it, 



20 THE REFRACTION OF THE EYE 

is more curved than the meridian at right angles to it. And 
since the vertical meridian, or one in the neighborhood of it, is, 
as a rule (perhaps in 75 to 80 per cent of all cases of astigma- 
tism), more curved than the horizontal, or the meridian at right 
angles to it, the astigmatism in such cases is said to be accord- 
ing to the rule, or " with the rule." French writers often call 
this " direct " astigmatism, while they designate astigmatism 
against the rule as " indirect " astigmatism. 

Many times beginners ask if hypermetropic astigmatism is 
not always with the rule, and if myopic astigmatism is not 
always against the rule. As a matter of fact, it makes no dif- 
ference whether the astigmatism be hypermetropic (simple or 
compound), myopic (simple or compound), or even mixed, just 
so the vertical meridian of the cornea or one within 45° of it is 
more curved than the meridian at right angles to it, that is 
astigmatism with the rule. 

In order that the reader cannot possibly go astray on this 
point, I will take an example of each form of astigmatism, and 
show by diagrams how it may be " with the rule " in every f orm.^ 




Fig. 9. 

1 Under the heading of astigmatism against the rule, I show how astigmatism 
may he " against the rule " in all its forms. 



ASTIGMATISM WITH THE RULE 



21 



1. Simple hypermetropic astigmatism, with the rule. — Figure 
No. 9 shows the vertical and horizontal sections of an eye with 
such an error of refraction. It is seen by this diagram that the 
vertical meridian is emmetropic and allows the rays of light to 
focus on the retina, and is more curved than the horizontal 
meridian which is flat and allows the rays of light to focus back 
of the retina. Therefore, according to our definition of astig- 
matism with the rule, this must be a case of it, for the vertical 
meridian is more curved than the horizontal. 

2. Compound hypermetropic astigmatism with the rule. — In 
such a case the vertical meridian is flat and allows the rays of 




Fig. 10. 

light to focus back of the retina, but it is not as flat as the 
horizontal meridian which allows the rays to focus still farther 
behind the retina. Here again the vertical meridian is more 
curved than the horizontal, and, of course, the astigmatism is 
with the rule, though it is compound hypermetropic. 

3. Simple myopic astigmatism with the rule. — Here the ver- 
tical meridian is myopic, causing the rays of light to focus in 
front of the retina, and is more curved than the horizontal 
meridian which is emmetropic, and allows the rays to focus on 



22 



THE REFRACTIOX OF THE EYE 



the retina. ISTow, this is with the rule, though it is myopic 
astigmatism — simply because the vertical meridian is the more 
curved. 




Fig. 11. 

4. Compound myopic astigmatism ivith the rule. — The verti- 
cal meridian is more myopic and at the same time more curved 



VERT. MERID, 




Fig. 12. 



than the horizontal meridian, which latter fact makes it astig- 
matism with the rule. 



ASTIGMATISM AGAINST THE RULE 



23 



5. Mixed astigmatism with the rule. — The vertical meridian 
is myopic and focusses rays of light in front of the retina, and 
is more curved than the horizontal meridian which is hyper- 
metropic (fiat, less curved), and focusses rays back of the retina. 
The astigmatism is with the rule, therefore, though mixed. 




Fig. 13. 



We see, then, by the above five diagrams that astigmatism 
may be with the rule in all of its forms ; the only thing neces- 
sary to have it such, the sine qua non, so to speak, is that the 
vertical meridian of the cornea or one in its neighborhood shall he 
more curved than the horizontal or the one at right angles to it. 

Where the vertical meridian of the cornea, or any meridian 
in the neighborhood of the vertical meridian, that is, within 
45° of the vertical, is less curved than the meridian at right 
angles to it, that is astigmatism against the 7^ule. 

. In other words, astigmatism against the rule means simply 
that the vertical meridian of the cornea is less curved than 
the horizontal ; and this condition may obtain in any form 
of astigmatism — hypermetropic (simple or compound), myopic 
(simple or compound), and in mixed astigmatism, as the fol- 
lowing diagrams show : — 



4 
I 



24 



THE refractio:n^ of the eye 



1. Simple hypermetropic astigmatism against the rule. — 
The vertical meridian is hypermetropic, focusses rays of light 
back of the retina, and is less curved than the horizontal 
meridian, which is emmetropic, and focusses rays on the retina. 




Fig. 14. 



2. Compound hypermetropic astigmatism against the rule. — 
Here both meridians are hypermetropic, but the vertical more 
so than the horizontal, consequently the vertical meridian is 




Fig. 15. 



ASTIGMATISM AGAINST THE RULE 



25 



less curved than the horizontal. The astigmatism is, therefore, 
against the rule. 

3. Simple myopic astigmatism against the rule. — The ver- 
tical meridian is emmetropic, focusses the rays on the retina, 




Fig. 16. 



and is less curved than the horizontal meridian, which is 
myopic, and focusses rays in front of the retina. 

4. Compound myopic astigmatism against the rule. — Here 
both meridians are myopic, but the vertical is less myopic than 




Fig. 17. 



26 



THE REFRACTION OF THE EYE 



the horizontal, is less curved, and consequently it is astig- 
matism against the rule. 

5. Mixed astigmatism against the rule. — The vertical me- 
ridian is hypermetropic, focusses rays back of the retina, and 
is less curved than the horizontal meridian, which is myopic, 
and focusses rays in front of the retina. 




Fig. 18. 

By the above diagrams we see that astigmatism may be 
against the rule in all its forms. So long as the vertical me- 
ridian of the cornea is less curved than the horizontal, that is 
astigmatism against the rule. 

I have gone very particularly and minutely into this point 
of astigmatism with the rule and astigmatism against the rule, 
because I have found in my teaching at the Post- Graduate 
School of Medicine that it is a point on which most beginners 
are in doubt. I may add that I have seen many others who 
have used the instrument for a long time not clear on the 
question. Some authors are inclined to give but little impor- 
tance to it, but I have found it of much value in instructing. 
Because, if, on finding the astigmatism with or against the 
rule with the ophthalmometer, you can teach the student to 



WHY THE MIRES OVERLAP AND SEPARATE 27 

picture in his " mind's eye," so to speak, the condition of cur- 
vature of the cornea and the position of the focal points of its 
two chief meridians of curvature in relation to the retina in 
the various forms of astigmatism, it greatly assists him in 
adjusting glasses. In fact, it makes him think of the eye under 
observation, and not of some abstruse rule in a text-book. 

Why the mires overlap in astigmatism with the rule; why 
they separate in astigmatism against the rule. — It is a well- 
known fact to those who have used the ophthalmometer, that 
in astigmatism with the rule, the images of the mires overlap 
when turned from the primary to the secondary position ; and 
that these same images in astigmatism against the rule separate 
when turned from the "primary" to the 
"secondary" position. ^ Why is this so? 

Figure 19 shows the general form of ^^° 
the cornea, front view, in astigmatism with 
the rule. 

,-_^ .., .,1 Fig. 19. — Showing front 

W e Will assume a case with the two view of an eye with 

chief meridians of curvature at 90° and astigmatism with the 

rule. 

180°, exactly. 

In such a case the "primary" position would be found 
(rule 5, p. 17) at 180°. If the inner edges of the images 
are then approximated and the arc turned 90° to the " second- 
ary " position, the doubled images of the object under measure- 
ment cannot become smaller from side to side (the deviation 
caused by the prism remaining the same), except by overlap- 
ping at their inner edges, which they do (see Fig. 8). And 
the greater the difference in curvature of the two chief merid- 

1 In passing, it may be said that the "primary " position is nothing more 
than the starting point, or the first position in wliicli the lines dividing the mires 
into halves become straight with each other, showing that one of the two chief 
meridians of curvature of the cornea has been found. Hence it is called the 
"primary" or first position. The " secondary" position is at right angles to 
the "primary" and is called "secondary" simply because it is the second posi- 
tion reached. 




28 



THE REFRACTION OF THE EYE 




180 



Fig. 20. — Diagram of 
front view of an 
eye with astigma- 
tism against the 
rule showing a ver- 
tical oval. 



iaus the more overlapping there will be in astigmatism with the 
rule. 

In astigmatism against the rule, just the reverse holds, that 
is, the images separate when turned from the primary to the 
secondary position. A glance at Fig. 20, 
which represents the general form of the 
cornea, front view, in astigmatism against 
the rule, easily explains this. 

Here the doubled images of the mires 
are approximated on a meridian with a 
shorter radius of curvature than the verti- 
cal meridian. Consequently, when the im- 
ages are turned to the secondary position, 
90° in this instance, to a meridian with a 
longer radius of curvature, the images must 
become larger. But since the deviation caused by the prism 
is a constant one (2.95 mm.), the doubled images cannot 
become larger from side to side, except by pulling apart or 
separating at their inner edges, which they do. 

The greater the difference in the radius of curvature of the 
two chief meridians the greater the separation of the images. 

With the above explanation, it is easy to see why the images 
always overlap when the astigmatism is with the rule and why 
they always separate when the astigmatism is against the rule. 
Consequently, when we have an eye under observation with 
the ophthalmometer, we know immediately, if on turning the 
arc from the primary position to the secondary position and an 
overlapping of the images occurs, that we have astigmatism 
with the rule. If, however, the images separate when the arc 
is turned from the primary to the secondary position, we know 
at once that the astigmatism is against the rule. 

The instrument, therefore, says something and means some- 
thing when the images either overlap or separate. If the 
images neither overlap nor separate on turning the arc from 



WHY ONE-HALF DIOPTER IS DEDUCTED 29 

the primary to the secondary position, it shows that there is no 
corneal astigmatism at all. In such cases the patient some- 
times takes a weak cylindrical glass (about .50 D.) against the 
rule, that is, + .50 D. cylindrical axis at 180° or near it, if the 
patient is hypermetropic ; or — .50 D. cylindrical axis 90° or 
near it, if the patient is myopic. This is explained by the 
presence of a small amount of lenticular astigmatism which is 
nearly always present, and against the rule.^ Consequently 
we should be on the lookout for this in such cases. Many 
times, however, when the ophthalmometer shows no corneal 
astigmatism the patient accepts no cylindrical glass at all. 

Why do we deduct half a diopter from the reading of the in- 
strument luhen the astigmatism is with the rule, and why do ive 
add half a diopter to its reading when the astigmatism is against 
the rule? The above question is often asked, and perhaps 
the correct answer and true explanation of same is to be found 
in the lenticular astigmatism present in most cases. 

1. In astigmatism with the rule we usually have to deduct 
half a diopter from the reading of the instrument, that is, the 
patient- will not accept as much as the instrument gives by 
.50 D. This can be explained quickest and best by an illus- 
trative case. Say the instrument reads astigmatism with the 
rule 2.50 D., axis 90° -f or 180° — . We will assume also, for 
the sake of simplicity, that it is a case of simple hyperme- 
tropic astigmatism. Figure 21 shows a vertical and horizontal 
section of such an eye and where the rays of light focus. A 
front view of the cornea and lens is also given in order to show 
the outlines of their front surfaces. It is evident that, in 
order to have the rays of light in the vertical meridian focus on 
the retina, both the cornea and the lens must be emmetropic 
in the vertical meridian. ^ 

1 Or it may be accounted for by an astigmatism of the posterior surface of 
the cornea, which sometimes amounts to as much as 1 D. 

2 At least their combined refractive power must be emmetropic in effect. 



80 



THE REFRACTION OF THE EYE 



But the horizontal meridian of the cornea is flatter by 
2.50 D. than the vertical meridian, as measured by the in- 
strument ; and if the patient had no lenticular astigmatism, 
it would require a + 2.50 D. cylindrical glass to correct this 
and bring the rays to a focus on the retina. But as a matter 
of fact in such a case the patient usually will accept but 2 D. 
cylindrical glass. This can be explained best, it seems to me, 
by assuming a lenticular astigmatism, myopic in nature, of 
.50 D. in the horizontal meridian. This would neutralize that 



VERT. MERID. 




M. .50 D. 



Fig. 21. — Vertical and horizontal sections of the right eye: also front view of the 
cornea and the lens ; simple hypermetropic astigmatism with the rule. 



amount (.50 D.) of the hypermetropic corneal astigmatism in 
the same meridian, leaving but 2 D. of total astigmatism to be 
corrected by a glass. 

What is true in hypermetropic cases is also true in myopic 
cases ; as see Fig. 22. 

Here the diagram shows a case of simple myopic astigmatism 
with the rule 2.50 D. axis 90°+ and 180° — . In order to have 
the rays of light in the horizontal meridian focus on the retina, 
both the cornea and lens must be emmetropic in the horizontal 
meridian (that is, their combined refractive power). But the 



WHY ONE-HALF DIOPTER IS ADDED 



31 



vertical meridian of the cornea is more curved than the horizon- 
tal by 2.50 D. as shown by the ophthalmometer, therefore it 
would require a— 2.50 D. cylindrical glass, axis 180°, to cor- 
rect it, if no lenticular astigmatism was present. As a rule the 
patient will accept but a — 2 D. cylindrical glass. This is to 
be accounted for by the lens being hypermetropic astigmatic 
.50 D. in the vertical meridian, thereby neutralizing that amount 
of the corneal astigmatism, and but 2 D. of total astigmatism 
is left to be corrected. 





Fig. 22. — Vertical and horizontal sections of the right eye ; also front view of the 
cornea and the lens; simple myopic astigmatism with the rule. 



The lenticular astigmatism is not always exactly .50 D., but 
may be more or less. Sometimes it is only .25 D., or may be 
absent. Again, it may amount to .75 D., or 1 D., and excep- 
tionally to even larger amounts. As a rule, however, it amounts 
to .50 D. or .75 D., and in astigmatism with the rule, it being 
of an opposite kind to the corneal astigmatism, it neutralizes 
to that extent the corneal astigmatism. And that is why we 
deduct such amount from the reading of the instrument Avhen 
the astigmatism is with the rule. 

2. In astigmatism against the rule we usually have to add 



32 



THE REFRACTION OF THE EYE 



a half diopter to the reading of the instrument, that is, the 
patient accepts that much more. 

Illustrative cases will serve to explain better than anything 
else. Say the ophthalmometer reads, astigmatism 2.50 D. 
against the rule, axis 180° + 90° — . To simplify matters we 
will assume it to be a case of simple hypermetropic astigmatism. 

It is plain from Fig. 23 that both the cornea and lens are 
emmetropic in the horizontal meridian because the rays of light 



VERT. MERID. 



HOR. MERID. 




H. 2.50 D. 
CORNEA 




Fig. 23. — Vertical and horizontal sections of an eye with simple hypermetropic 
astigmatism against the rule; also front view of the cornea and the lens in 
outline. 

passing through this meridian focus on the retina. But the in- 
strument shows the vertical meridian of the cornea to be flatter 
by 2.50 D. than the horizontal meridian ; and if no lenticular 
astigmatism was present it would take a -f2.50 D. cylindrical 
glass axis 180° to correct same. As a matter of fact, the patient 
usually accepts a half diopter more than the instrument says. 
This can be accounted for by a half diopter (.50 D.) of len- 
ticular astigmatism in the vertical meridian, hypermetropic in 
nature, and, therefore, of the same kind as the corneal astig- 
matism. In other words, both the cornea and lens are hyper- 
metropic in the vertical meridian, the cornea 2.50 D. and the 



PRINCIPAL MERIDIANS AT 45° AND 135° 33 

lens .50 D., the two added together making 3 D. the total 
astigmatism, consequently it requires a + 3 D. cyl. axis 180° 
to correct same. 

The same law holds true in myopic cases. 

Many times, however, in astigmatism against the rule, the 
patient accepts exactly the glass indicated by the ophthal- 
mometer, showing that lenticular astigmatism is often entirely 
absent in such cases. 

The whole of the explanation given above on this question 
may be summed up in two short sentences. 

1. In astigmatism with the rule the lenticular astigmatism is 
in the same meridian as the corneal astigmatism, but is of an 
opposite kind, and usually amounts to lialf a diopter, thereby 
neutralizing that amount of the corneal astigmatism. 

2. In astigmatism against the rule the lenticular astigma- 
tism is in the same meridian as the corneal astigmatism, is of 
the same kind, and usually amounts to half a diopter, therefore 
adds that amount to the corneal astigmatism. ^ 

Before closing this chapter there is one final point I wish to 
elucidate, and that is the reading of the ophthalmometer when 
the two chief meridians of curvature of the cornea happen to 
be at 4,5° and 135°, or exactly halfway between 0° and 90° on 
one side, and 90° and 180° on the other side. 

We know that in astigmatism both with and against the rule 
that the two main meridians of curvature of the cornea are at 
90° and 180°, or in their neighborhood. When the meridian 
at 90° or its neighborhood is the more curved, as it usually is, 
it is astigmatism with the rule ; but if this meridian happens to 
be less curved it is astigmatism against the rule. 

There are certain exceptional cases where the two chief 
meridians of curvature of the cornea are just halfway be- 

1 1 am not unmindful of the fact that the unequal curvature of the posterior 
surface of the cornea can and may modify the astigmatism of the front surface 
of the cornea. I think, however, the lens plays the more important role. 




34 THE REFRACTION OF THE EYE 

tween 0° and 90°, and 90° and 180°, that is, exactly at 45° 
and 135° (see Fig. 24). 

Now 45° is no nearer to 90° than it is 

90° 

135^^^ — PX^s" ^^ ^°' consequently it is not in the neigh- 

borhood of one or the other. So with 
135° as regards 90° and 180°, it is just 
as near one as the other, and is not in 
Fig. 24. -Front view of the neighborhood of either. 

an eye showing the ttt-i , ^ j • t. 

two chief meridians What are we to do m such a case as 

of curvature at 45" regards " astigmatism with the rule " and 
" astigmatism against the rule " ? Strictly 
speaking, in such cases, there is no such thing as " astigmatism 
with the rule " and " astigmatism against the rule," simply 
because the two chief meridians of curvature are exactly on 
the halfway mark or dividing lines of what it takes to make 
astigmatism with, or against, the rule. But how does the 
ophthalmometer work in such cases ? In such cases we search 
for the primary position as usual (see rule 5, p. 17), by begin- 
ning with the long indicator at 0°. We know when we are 
in the primary position by the two narrow black lines which 
divide the mires into halves becoming straight with and oppo- 
site each other, which they do when either of the chief meri- 
dians of curvature of the cornea is reached. In the present 
case these lines would not be straight when we turned the 
long indicator to 0°, because neither of the chief meridians 
is here. Following the directions in rule 5, we turn the long 
indicator from 0° toward 135°, when 135° is reached (one 
of the chief meridians of curvature in this instance) the narrow 
black lines dividing the mires become straight with each 
other. This is the primary position. We then approximate 
the images and turn the arc at right angles to the primary 
position (the long indicator to 45°) to obtain the secondary 
position. If the meridian at 45° proves to be more curved 
than the one at 135° the images will overlap. 



PRBSrCIPAL MERIDIANS AT 45° AND 135° 35 

According to the language of the instrument, that is, 
when overlapping occurs, it means astigmatism with the rule, 
this would be a case of astigmatism with the rule. Though, 
as a matter of fact, we know and have just explained above, 
that there is really no such thing as astigmatism with or 
against the rule, when the chief meridians of curvature are at 
45° and 135°. However, for the sake of uniformity of expres- 
sion and to make the words of the instrument overlapping 
and separation of the images mean a definite something in 
every case^ it is well to apply the terms "astigmatism with 
the rule " and " astigmatism against the rule," even to the 
meridians at 45° and 135°. 

It is altogether important also in such cases to take either 
135° or 45° — one or the other — always as the primary posi- 
tion, and not first one and then the other as the primary posi- 
tion. A glance at Fig. 24 will show why this is necessary. 
If we start at 135° as the primary position, the meridian of 
longest radius of curvature, and then turn to 45°, the secondary 
position, to the meridian of shortest radius of curvature, the 
images will overlap, showing astigmatism with the rule. How- 
ever, should we take 45° as the primary position, the meridian 
of shortest radius of curvature, and then turn to 135°, at right 
angles, a meridian with the longer radius of curvature, the 
images would separate, showing thereby astigmatism against 
the rule. In other words, the instrument would say astigma- 
tism with the rule and against the rule, in the same eye^ accord- 
ingly as we assumed 135° or 45° as the primary position. As 
we cannot very well have astigmatism both with and against the 
rule in the same eye, it is best, in such cases as the above, to 
assume one or the other of these meridians always as the pri- 
mary position. Individually, and in the rules which I have 
formulated for the use of the instrument, I assume 135° always 
as the primary position in such cases. The meridian at 45° 
could be taken just as well, provided it was always taken as 
the starting or primary position. 



CHAPTER III 

GENERAL CONSIDERATIONS IN THE USE OF THE OPHTHAL^ 
MOMETER — SIMPLE HYPERMETROPIC ASTIGMATISM— SIMPLE 
HYPERMETROPIA — ILLUSTRATIVE CASES 

It is well to state here that the ophthalmometer does not, 
except in an indirect way, which is not at all reliable, indicate 
the nature of the error of refraction, that is, if it is hyper- 
metropic or myopic in character. All that it does is to measure 
the front surface of the cornea. If the cornea is uniformly 
curved in all of its meridians, the instrument shows it by the 
images of the mires not overlapping or separating in any posi- 
tion after they have once been brought in apposition. If the 
cornea is not uniformly curved,^ that is, if astigmatism is pres- 
ent, it measures the difference in the radius of curvature of 
the two chief meridians, thereby measuring the amount of the 
astigmatism ; and also indicates the position of these two chief 
meridians. Of the nature of the error, if hypermetropic or 
myopic, we have to find out by the use of the trial lenses, the 
ophthalmoscope, the retinoscope, and at rare intervals we may 
be obliged to use atropine or some other mydriatic in addition ; 
for, as above stated, the ophthalmometer points to the nature 
of the error only in an indirect way, as follows : for example, 
say we find the primary position at 0° or 180°, and that when 
the images of the mires just touch in this position that the 
radius of curvature on the cornea in this meridian is just 

1 Of course it is a well-established fact that the cornea is slightly elliptical in 
shape, but when the images of the mires neither overlap nor separate at any- 
meridian on the cornea after once approximated, we may say it is spherical in 
shape. 



GENERAL CONSIDERATIONS 37 

7.8 mm., which is the average radius of curvature of a normal 
cornea. By noticing the position of the graduated mire in its 
relation to the millimeter marks on the anterior edge of the arc, 
in such a case, it will be seen that the fine mark or line on the 
base of the mire stands just at 7.8 mm. Say now we turn the 
arc to the second position and the images overlap five steps. 
This would show that the vertical meridian was more curved 
than the horizontal, and to the extent of 5 diopters. If, then, 
in this position the images are withdrawn from their overlap- 
ping, so that they just touch again, it will be found that the 
fine mark on the graduated mire stands opposite, or nearly so, 
the 7 mm. mark, showing a shorter radius of curvature in this 
vertical meridian. 

Since the horizontal meridian had the normal radius of cur- 
vature, the vertical meridian with a shorter radius of curvature- 
would indicate, indirectly to be sure, myopic astigmatism iu 
the vertical meridian. On the other hand, had one found the 
horizontal meridian with a considerable longer radius of curva- 
ture than the average, say 8.5 mm., and then on turning to the 
vertical meridian, or second position, we found the radius of 
curvature in this meridian to be just 7.8 mm., the average 
radius of curvature, we might assume that the horizontal 
meridian in this instant was hypermetropic in nature on ac- 
count of its long radius of curvature, 8.5 mm. 

Valk, in an examination of over five hundred cornefe with 
the ophthalmometer, found the average normal radius of curva- 
ture to be only 7.65 mm., a considerable shorter radius than is 
commonly accepted as the average (7.8 mm.). 

Proceeding on this assumption, he draws the following con- 
clusion from his examination of cases : — 

"That the radius of curvature bears a certain definite rela- 
tion to the refractive condition of the eyes, in which, if we find 
that the radius of curvature is greater than 7.65 mm., that the 
refraction is probably hypermetropic, as we find only one in 



38 THE REFRACTION OF THE EYE 

ten myopic ; on the other hand, if the radius of curvature is 
less than 7.60 mm., that the refraction is myopic, as now the 
proportion is found to be one in three." ^ 

In this conclusion he differs from almost all other observers. 
Bonders ^ long ago made similar measurements, and came to the 
conclusion that there was no definite relation between the radius 
of curvature of the cornea and the refractive condition of the 
eye. He says : " A priori it might be supposed, and it has 
been not only supposed, but also asserted, that less convexity 
of the cornea and of the crystalline lens is peculiar to the hyper- 
metropic eye. So far as the cornea is concerned, I am justified 
by the results of numerous accurate determinations, in denying 
the assertion. Even in high degrees of H., the radius in the 
visual line (compare p. 89) is nearly equal to that in the em- 
metropic eye ; in the highest degrees, when the circumference 
of the cornea is somewhat less than usual, I found the radius 
even less." ^ 

The same author draws a similar conclusion in regard to 
myopia, that is, that the radius of curvature of the cornea 
bears no definite relation to the refractive condition present. 

In extreme degrees of myopia, on the contrary, a somewhat 
flatter cornea is met with.* 

He, of course, admits such a thing as curvature myopia and 
hypermetropia, but his ultimate conclusion is, " That myopia 
usually depends upon an elongation^ and hypermetropia upon a 
shortening^ of the axis of vision.^' All subsequent observers have 
confirmed this view. 

Schiotz^ also has made special investigation with the ophthal- 
mometer as to the corneal curvature in cases of hypermetropia, 

1 Ophthalmic Eecord, June, 1897. 

2 Accommodation and Befraction of the Eye, pp. 88, 89, 246. 

3 Ibid., p. 246. 
^ Ihid., p. 88. 

5 Cited by A. Javal, Jr. , System of Diseases of the Eye, Norris and Oliver, 
Vol. H, p. 127. 



significa:n^ce of radius of curvature of cornea 39 

myopia, and emmetropia, but found no definite law or relation 
to exist. 

A. Javal,^ in commenting on this subject, says : — 

" It is, in fact, remarkable how greatly the radius of curva- 
ture may vary for the same refractive condition. In emme- 
tropia the radii of curvature as measured by Schiotz varied 
between the limits 8.657 mm. and 7.243 mm., or, in diopters, 
between 38.8 D. and 45.3 D., — a difference of not less than 
6.5 D. 

" From these figures it would appear that variations in the 
radius of corneal curvature do not play any great role in 
determining the refraction. 

" A still more conclusive proof is afforded by observations 
made on antimetropes. As a rule, in such persons we find the 
same radius of corneal curvature in both eyes, even when one 
of these eyes is highly myopic." 

I must say that my experience has been that of the great 
majority of observers, in not finding any definite relation to 
exist between the radius of corneal curvature and the refractive 
condition of the eye. And even if the definite relation that 
Valk claims existed, it would be of no value in the fitting of 
glasses. For under the most favorable circumstances, that is, 
where the radius was found by the ophthalmometer to be less 
than 7.60 mm., my5pia was absent in QQ^ per cent of the cases ; 
while in the most unfavorable conditions, that is, where the 
radius was over 7.65 mm., it was absent in 90 per cent of the 
cases. Therefore on an average it failed in 78 per cent of all 
cases, or was right in but 22 per cent of cases. When it is 
remembered that myopia forms 16 to 20 per cent of all refractive 
cases, take them as they come, it will be seen of what little 
value Valk's definite relation of corneal radius to the existing 
refractive condition amounts to. 

The ophthalmometer then shows the presence or absence 

1 Loc. cit. 



40 THE REFRACTION OF THE EYE 

of astigmatism ; if present, whether it is with or against the 
rule, the amount, and the axes of the main meridians. It does 
not, except in a very indefinite way, as just pointed out above, 
indicate the character of the error of refraction, whether hyper- 
metropic or myopic. This latter point, in the great majority of 
cases, is easily determined, and most of the time by the simple 
subjective test with the test cards and trial lenses, that is, if the 
test is begun properly. If not revealed by the trial lenses, then 
further objective tests with the ophthalmoscope and retinoscope 
will reveal the nature of the error, except in a very limited 
number of cases in subjects under twenty years of age, when a 
mydriatic must be called into requisition. 

In my practice, both private and hospital, I do not use a 
mydriatic in more than one per cent of all cases of refraction. 
And I may say here, that I agree with my illustrious teacher 
and preceptor, D. B. St. John Roosa, on this point, that it is 
not necessary to use atropine or mydriatics of any kind, except 
in rare instances.^ The soundness of this practice is amply 
borne out in my private practice and in the clinic at the 
Manhattan Eye and Ear Hospital. In 1891 I took all the 
cases of refraction consecutively that came to the clinic of 
Drs. Roosa and Lewis, and found that a mydriatic was used 
but once in every sixty-four cases, or in about 1.5 per cent of 
all cases of refraction. In 1896, in the same clinic for a period 
of six months, atropine was not used in a single case uncompli- 
cated with squint.2 

In squint cases it is advisable to use a mydriatic so as to 
give a full, or almost full, correction of the error of refraction, 
and in that way aid in straightening the eye. But in ordinary 
uncomplicated cases of refraction, I repeat, it is rarely necessary 
or advisable to use any mydriatic whatever. Furthermore, it 

1 Hirschberg, George J. Bull, Dennett, and many others hold the same 
opinion as to the use, or rather non-use, of mydriatics. 

2 D. B. St. John Roosa, Manhattan Eye and Ear Hospital Beport, 1896. 



ROUTINE OF EXAMINATION 41 

may be remarked that since we have used the ophthalmometer 
at the Manhattan Eye and Ear Hospital clinics, and depended 
on it almost to the exclusion of atropine, that we have changed 
fewer glasses than formerly, when atropine was used in nearly 
every case under forty years of age. The same holds true in 
my private practice. 

When we take into account the time and great annoyance 
saved to the patient by not using atropine, we can readily see 
the.advantages of an ophthalmometer. In fact, many business 
men will not tolerate a mydriatic ; and one can hardly blame 
them when it is known that their eyes can be tested, with rare 
exceptions, just as well or better without atropine than with it. 

If the following routine of examination, which I shall now 
give, is followed out, 99 per cent of all uncomplicated cases of 
error of refraction can be fitted without the use of mydriatics. 

1. Use the ophthalmometer. 

2. Use trial lenses and test cards. 

3. Use the ophthalmoscope. 

4. If after two tests on different days the result is still 
unsatisfactory, employ a mydriatic and use the retinoscope in 
addition to the other tests. 

The reason that I do not, as a rule, use the ophthalmoscope 
before testing with the trial lenses is that if light is thrown 
into the eye for a prolonged time, it dazzles the sight and 
impairs the value of an immediate test with the trial lenses. 
If I have much trouble, however, in finding the proper glass, 
I do not hesitate to use the ophthalmoscope to find the nature 
of the error of refraction, or if any pathological condition of 
the eye exists ; then let the patient wait a short while before 
the subjective test with the trial lenses is again undertaken. 

Simple cases of hypermetropia and myopia are, as a rule, 
easily fitted to glasses ; but a certain definite method should 
be followed even in these cases. It is the astigmatic cases 
that give most trouble, and among these, as is well known, the 



42 THE REFRACTION OF THE EYE 

compound hypermetropic and mixed astigmatisms are the most 
difficult to fit. 

Astigmatism is the thing of most importance in correcting 
errors of refraction, and I invariably correct the astigmatism 
first, unless there is a large amount of spherical error present 
— a myopia of 8 diopters or more, or a hypermetropia of 6 
diopters or more — with only a small amount of astigmatism. 
In such cases, part of the spherical error is first to be corrected, 
in order, if possible, to bring up the vision sufficiently, so that 
the eye will appreciate any further change in acuity of vision 
when a weak cylindrical glass is placed in front of it. 

I always begin my test by putting on plus glasses ; plus 
cylindrical glasses if astigmatism is present, plus spherical 
glasses if astigmatism is absent, and for the following reasons : 
First, because we do not know if the patient is hypermetropic 
or myopic. If the patient happens to be hypermetropic, plus 
glasses are accepted, as a rule, if begun with ; however, if minus 
glasses are first tried, the patient many times accepts them, 
especially if the error is of low amount, though the patient is 
really hypermetropic. This fact is so well known that it is 
hardly necessary to more than merely allude to it. The eye 
instinctively makes an effort to overcome minus glasses when 
placed in front of it, the ciliary muscle is thrown into a spasm 
of accommodation, producing an artificial myopia, which the 
minus glass partly or wholly corrects, and in this way appar- 
ently improves vision. The mere fact that a patient accepts 
minus glasses is no indication whatever that he has myopia. 
Furthermore, minus glasses should never be tried until plus 
glasses have been tried, unless we know beforehand that the 
patient is really myopic, for they tend to incite a spasm of 
accommodation, which is the very thing we wish to avoid. 

The thing of next importance to plus glasses in beginning a 
test is that we shall begin with the weakest lenses in the trial 
case, and go up gradually. I do this also to avoid spasm of 



ROUTINE OF EXAMINATION 43 

accommodation, for by adding a quarter of a diopter at a time 
the eye accustoms itself to it, and the ciliary muscle relaxes 
gradually if it is only given a chance. 

Should all, or almost all, of the correction be put on at once, 
however, the change for the eye is so sudden and marked that 
it will not adjust itself to it ; whereas, had the glasses been 
gradually increased in power, the ciliary muscle would have 
relaxed. This is my experience, and I believe it accords with 
that of the great majority of observers. ^ 

By following this plan, spasm of accommodation, if present, 
can, in the great majority of cases, be overcome, and if not 
present, the liability of causing it be avoided. 

Another method of avoiding spasm of accommodation, and 
one well known among oculists, is to correct both eyes at the 
same time. 

Not only do I follow the above routine, but under step No. 
2 I follow a certain routine in putting the glasses in the trial 
frames during the subjective tests. Bearing in mind always to 
begin the test with a plus glass (unless we know beforehand 
the patient to be myopic), and a weak plus glass, and to grad- 
ually increase the strength of the glass, in order to avoid or 
overcome spasm of accommodation, I proceed in the following 
manner : When the ophthalmometer indicates astigmatism, first 
try plus cylindrical glasses alone ; second, plus spherical glasses 
in addition ; third, minus cylindrical glasses at right angles to 
the plus cylindrical glass, if vision is not made perfect ^ b}^ a 

1 Some oculists, however, resort to putting on very mucli too strong plus 
glasses, which blur the vision completely, and in that way take away the desire 
to accommodate for or fix on any object. Then, by gradually diminishing the 
power of the glass, the correct glass is finally accepted. For myself, I much 
prefer to begin with the weakest, and work up. 

2 For instance, if the ophthalmometer should indicate 4 diopters of astigma- 
tism, with the rule, 90°+ or 180° — , and the patient would accept only +2 D. 
cyl, axis 90°, with improvement of vision, but would accept no plus spherical 
glass in addition, mixed astigmatism is at once suspected, and minus cylindrical 
glasses are tried at right angles to the plus cylinder. 



44 THE REFRACTION OF THE EYE 

plus cylindrical glass alone, and plus spherical glasses are not 
accepted in addition ; fourth, minus cylindrical glasses alone ; 
fifth, minus spherical glasses in addition. 

When the ophthalmometer indicates but one-half a diopter 
of astigmatism with the rule, usually the lenticular astigmatism 
neutralizes that amount of corneal astigmatism, and the patient 
will not accept any cylindrical glass. In such cases we are 
most of the time dealing with cases of simple hypermetropia 
and myopia, and proceed at once to try plus spherical glasses, 
and, if not accepted, minus spherical glasses. However, should 
there be only a very small amount of hypermetropia or myopia, 
and the patient's sight is not improved by the spherical glasses, 
it is well to try a weak cylinder, plus first, then minus. This 
is for two reasons : first, we may have made an error with the 
ophthalmometer in the estimation of the amount of the astig- 
matism ; second, the lenticular astigmatism might not be suffi- 
cient to neutralize the half diopter of corneal astigmatism, or it 
might more than neutralize it, when it would result in a small 
amount of astigmatism against the rule. 

It has been maintained by some authorities that the ophthal- 
mometer is not of value in cases of simple myopia and hyper- 
metropia, an opinion from which I beg to differ. In cases of 
hypermetropia and myopia it eliminates the question of corneal 
astigmatism. This is a very important factor, for with no 
astigmatism present the tests for glasses are usually very easily 
made. The ophthalmometer is of great value in a negative way, 
therefore, even in cases of simple hypermetropia and myopia. 

Illustrative cases of simple hypermetropic astigmatism and 
hypermetropia. — In giving illustrative cases I shall first take a 
typical case, giving the tests for its detection and correction in 
detail ; then other cases showing different amounts of astig- 
matism and different axes, and cases against and with the rule 
will be taken. In many cases diagrams of the sections of the 
eye under observation through its two chief meridians of cur- 



ILLUSTRATIVE CASES 45 

vature are given. ^ This is done in order to have the reader 
think of the eye as it is^ to see where the rays of light entering 
such an eye focus, and how the proper glasses correct the error 
of refraction in such a case. It has been my experience that 
students at least do not think of the eye under observation, but 
try to fit the patient to glasses by following some rule in a book. 
They put the glasses on empirically; if they improve vision, 
very well, they are satisfied with that and do not worry them- 
selves much about the why or the wherefore; if the glasses do 
not improve vision, they are at a loss to know why, and many 
times give a wrong glass. Beginners, especially, are in doubt 
in cases where there is marked amblyopia present, where a 
patient will accept even a strong plus glass without improve- 
ment in vision. This is a common occurrence in cases of con- 
vergent squint, where, as is well known, usually a large amount 
of hypermetropia is present, especially in the squinting eye. 
Though there may not be any lesion of the fundus in either 
eye, the squinting eye is usually very weak-sighted or amblyopic, 
and will accept plus glasses without improvement in vision, or 
with only very slight improvement. It is very important that 
such an eye should have the right glass, yet, if the examiner is 
not sure of the correctness of his examination and correctly 
informed in optics, he might hesitate as to giving the glasses 
on account of the lack of improvement in vision. It is in just 
such cases of amblyopia, especially when the amblyopia happens 
to be in the case of a child or an ignorant person, that the 
ophthalmometer is of such great advantage. 

Case I. Corneal astigmatism with the rule^ 1 D., axis 
90° -f or 180°-; Patient accepts + .^0 B. cyl,, axis 90°.— 
April 6, 1892, Nellie H., aged twenty-three years, in good gen- 
eral health, has had trouble with her ej^es for about two years. 
After any continuous work, especially at night, her eyes burn 

1 These diagrams are not meant to be mathematically correct, and are used 
:simply to make the subject matter plainer. 



46 



THE REFRACTION OF THE EYE 



VERT. MERID. 





and ache, and often headaches follow. There is some redness 
of the edges of the eyelids and congestion of the conjunctiva. 
Ophthalmometer. — Astigmatism with the rule, 1 D., axis 
90° + or 180° - in each eye. 

Figure 25 shows the general shape of the cornea, front 
view, in this case. Since the astigmatism is with the rule, the 

vertical meridian must be 
more curved, that is, have^ 
a shorter radius of cuiwa- 
ture than the horizontal. 

We do not know, how-^ 
ever, from the examination 
with the ophthalmometer 
whether the error of refrac- 
tion is hypermetropic or 
myopic in character — that 
must be found out by sub-- 
sequent tests. 

Unless from the history 
of the case I have reason 
to suspect some pathological lesion of the eye, I next try the 
trial lenses and test cards. I do this, first, for the very good 
reason that most cases reveal the nature and extent of the 
error of refraction simply by the use of the ophthalmometer 
and trial lenses; second, because we do not have to delay the 
test with the trial lenses as we do where the ophthalmoscope ia 
first used, for the light thrown into the eye by an extended 
ophthalmoscopic examination dazzles the eye and requires some 
delay afterward before the subjective test can be completed. 

Test cards and trial lenses. — The horizontal lines on Green's, 
clock dial were seen plainest in this case. 

I^- ^- = M - • ff W- + -^^ D. cyl., 90°. 
L. V. = 1^ - : ff W. + .50 D. cyl., 90°. 
Reads Jaeger No. 1 from 6 to 15 inches. 




Fig. 25. 



ILLUSTRATIVE CASES 47 

Bearing in mind to correct the astigmatism first, if any is 
present, and proceeding with the test, as directed on page 42, 
by beginning with a weak plus glass, the first glass tried 
was + .25 D. cyl., 90° (as indicated by the ophthalmometer). 
This improved vision somewhat, so the next stronger cyl., 
+ .50 D., axis 90°, was tried; this improved vision still more. 
The next stronger cyl., + 75 D., axis 90°, made the vision 
worse. A + .50 D. cylindrical glass then was the strongest 
cylinder that gave the best vision. To see if any manifest 
hypermetropia was present in addition to the astigmatism, 
+ .25 D. spherical glass was placed in front of the + .50 D. 
cylindrical glass; it made vision worse, showing no manifest 
hypermetropia to be present. 

The same mode of procedure was followed in the left eye, 
the patient accepting a + .50 D. cylindrical glass, axis 90°, 
and obtaining the best vision, |^ in each eye. 

Ophthalmoscope. — Hypermetropic astigmatism with the 
rule, .50 D., axis 90°, in each eye; no pathological lesion of 
the fundus in either eye. 

The patient accepted the same glass on the second test, two 
days later and + .50 D. cyl., axis 90°, was prescribed for each 
eye. 

The retinoscope and mydriatics were not used in this case, 
as they were not deemed necessary. A mild astringent wash 
was prescribed for the slight inflammation of the lids. Octo- 
ber 17, 1895, three and a half years later, the patient returned 
on account of a slight conjunctivitis. With mild astringents 
this was cured in three weeks' time. The glasses were still 
satisfactory. 

Case II. Astigmatism with the rule, 4 D., axis 10°, to the 
temporal side of the vertical meridian in each eye; Patient com- 
plains of no asthenopia, hut simply of poor vision; Accepts 3.50 
D. cyl. in each eye. — December 5, 1894, O. M., aged twenty- 
six years, in robust health, consulted me on account of poor 



48 THE REFRACTION OF THE EYE 

vision. The remarkable thing about this case is that the 
patient never complained of asthenopia, though the tests 
showed him to have such a high degree of hypermetropic 
astigmatism. He never saw well, and noticed at school that 
he could not see as well as his companions. At night he 
could not read ordinary print. 

Ophthalmometer. — Astigmatism with the rule, 4 D., axis 
100° + or 10° - right eye ; 4 D., axis 80° + or 170° - left eye. 

Test cards and trial lenses. — 

R. V. = JJL: |o w. + 3.50 D. cyl., 100°. 
L. V. = 2^%: fl W. + 3.50 D. cyl., 80°. 

Reads Jaeger No. 1 from 4 to 12 inches. 

Ophthalmoscope. — Simple hypermetropic astigmatism in 
each eye. Two days after the first test a second test was 
made, and the patient accepted the same glass, which was 
ordered. The patient was seen two years later and the glasses 
were satisfactory. 

Case III. Corneal astigmatism with the rule .50. i)., neu- 
tralized hy lenticular astigmatism ; Patient accepts simple plus 
spherical glass. — October 3, 1893, M. B. H., aged thirty- 
three, general health is very good, but she is not robust. 
She complains of headaches and blurring of vision when she 
reads. The patient has worn glasses for the last two years, 
but without benefit. 

Ophthalmometer. — Astigmatism with the rule, .50 D., axis 
90°+ or 180° -each eye. 

Test cards and trial lenses. — All of the lines on the clock 
dial are seen with equal clearness. 

R. V. = 1^ + : If W. + 2.75 D.s. 

L.V. = || + :|^W. +3.75D.S. 

Reads Jaeger No. 1 at 6 inches. 



ILLUSTRATIVE CASES 49 

Ophthalmoscope. — H. 3D. right ; H. 4 D. left, with normal 
fundi. 

It will be observed in the above case that although the 
ophthalmometer showed corneal astigmatism of half a diopter 
with the rule, axis 90°+ or 180°—, that the patient did not 
accept any cylindrical glass. 

Following the rule laid down by Javal, and since confirmed 
by many observers, that when the instrument reads astigma- 
tism "with the rule" .50 D. usually must be subtracted from 
the reading, it will be seen that no astigmatism is left for 
correction in the above case. As fully explained, page 29, the 
lenticular astigmatism (or the action of the lens ?) in stich 
cases is in the same meridian as the corneal astigmatism, 
amounts as a general thing to .50 D., and is of an opposite 
kind! to the corneal; therefore it neutralizes the corneal 
astigmatism just to that extent. 

Sometimes the lenticular astigmatism amounts to but .25 
D., and sometimes it is entirely absent. Again, it may amount 
to a whole diopter or a diopter and a half, and in very excep- 
tional cases to even more. So constant, however, is the len- 
ticular astigmatism of .50 D., that, when we find that the 
patient does not accept the cylindrical glass as indicated by 
the ophthalmometer to within .50 D., it is well to take a 
second, a third, and even a fourth reading with the instrument, 
to see if we have not really made an incorrect reading. 
From my own experience I would say that the lenticular 
astigmatism generally amounts to just .50 D., next to this to 
.25 D., next to this .75 D., and next to this 1 D. 

Case TV. Corneal astigmatism with the rule^ .25 i)., neii- 
tralized hy the lenticular astigmatism-; Patient accepts simple 
spherical glasses. — I. W. S., aged twenty years, general health 

1 That is, if the horizontal meridian of the cornea is less curveei by .50 D. 
than the vertical meridian, then the horizontal meridian of the lens is more 
curved by .50 D. than the vertical meridian. 



50 THE REFRACTION OF THE EYE 

first class. He is a hard student ; his eyes ache and the vision 
blurs in the afternoon and evening. 

Ophthalmometer. — Astigmatism with the rule, .25 D., axis 
90° + or 180° - in each eye. 
Test cards and trial lenses. — 

R.V. =f^:ff W. + .50D.S. 
L. V. =|^:|f W. +.50D.S. 

Reads Jaeger No. 1 at 6 inches. 

Ophthalmoscope. — Hypermetropia 1 D. each. 

As this patient was from a neighboring state and had to 
return, I ordered glasses after one test, +.50 D.s, for each eye. 
They relieved his headaches and painful vision, and he was 
able to finish his schooling. 

In this case the corneal astigmatism of .25 D. was exactly 
neutralized by a lenticular astigmatism of .25 D. ; the lenticular 
not amounting to its usual .50 D., in which case it would have 
over-neutralized the corneal astigmatism of .25 D. 

Case V. Corneal astigmatism with the rule^ .25 i)., with no 
lenticular astigmatism. — Sometimes the patient accepts the 
exact amount of astigmatism indicated by the ophthalmometer, 
even Avhen the astigmatism is with the rule. This shows that 
in some instances there is no lenticular astigmatism at all, but 
only corneal. The present case illustrates this. 

March 2, 1892, Catharine H., aged twenty years, is in good 
health, but her eyes have been weak since a child; she has had 
many styes, and the eyelids are red most of the time. There is 
a well-marked blepharitis marginalis now. Typical asthenopia. 

Ophthalmometer. — Astigmatism with the rule, .25 D., axis 
90° + or 180° - in each eye. 

Test cards and trial lenses. — 

R. V. = ff : ff + W. + .25 D. cyl., 90°. 
L. V. = ff : ff + W. -f .25 D. cyl., 90°. 

Reads Jaeger No. 1 at 4 inches. 



ILLUSTRATIVE CASES 51 

Ophthalmoscope. — Hypermetropia .50 D. each. 

A solution of boracic acid was given to cleanse the eye with 
twice a day, and a weak ointment of yellow oxide of mercury 
to rub on the lids at night, although she stated that she had 
used this same ointment before without effect. 

Two days after, she was tested a second time and accepted 
the same glass as on the first test. The lids were in about the 
same condition as when first seen. A plus .25 D. cylindrical 
glass, axis 90°, was ordered for each eye. With these glasses 
the redness of the lids were entirely relieved, the styes ceased 
to return, and she used her eyes with comfort. 

While this case is reported primarily to show that there 
may be only corneal astigmatism present, and in a very small 
amount, it incidentally shows the value of very weak cylindri- 
cal glasses in some cases. It is well known that weak cylin- 
drical glasses (.25 D.), when worn against the rule or at slanting 
axis, often give marked relief, but they sometimes are of great 
benefit when worn with the rule and at symmetrical axis, as 
shown in the present case. 

The ophthalmometer is of the greatest service in fitting 
correctly such cases. 

Case VI. Qomeal astigmatism ivith the rule, .50 i)., with 
no lenticular astigmc^ism. — December, 1896, Ruth M., aged 
twenty-six, is in robust health, but the eyes pain and the 
vision blurs when she sews or reads for a little time. 

Ophthalmometer. — Astigmatism with the rule, .50 D., axis 
90° 4- or 180° - in each eye. 

Test cards and trial lenses. — 

R. V. = 1^ : ff W. -f- .50 D. cyl., 90°. 
L. v. =|^:ffW. -f.50D. cyl.,90°. 

Reads Jaeger No. 1 at 7 inches. 

Ophthalmoscope. — Emmetropia in the vertical meridian, 
and hypermetropia of .50 D. in the horizontal meridian. 



52 THE REFRACTION OF THE EYE 

On a second test the same glass was accepted and prescribed, 
which gave satisfaction. 

Case VII. Corneal astigmatism with the rule, 1 D. right 
eye and .75 B. left eye ; No lenticular astigmatism. — G. W. G., 
aged thirty-five years, general health good. He has worn 
glasses for four or five years, but not with comfort. Styes 
have troubled him from time to time also in the last four years. 

Ophthalmometer. — Astigmatism with the rule, 1 D., 105° -|- 
10° - right eye ; .75 D., 75° + or 165° - left eye. 

Test cards and trial lenses. — 

R- ^- = H • M W. + .75 D. cyl., 105°. 
L. V. = 1^: 1^ W. + .75 D. cyl., 75°. 

Reads Jaeger No. 1 at 7 inches. 

Ophthalmoscope. — Simple hypermetropic astigmatism with 
the rule, 1 D. each, axis 105° right and 75° left. 

Second test ; the ophthalmometer showed the same reading, 
the axis in the right eye being two or three degrees nearer to 
the vertical meridian perhaps. 

Test cards and trial lenses. — 



R. 


V. 


= u 


u 


+ w. 


+ 1D. 


cyl., 


105°. 


L. 


V. 


= 1* 


u 


+ w. 


+ .75 D. cyl 


,75° 



This last glass was ordered, but in about three months' time 
the axis of the right glass had to be shifted from 105° to 100°, 
a distance of 5°, when the glasses gave perfect comfort, and 
continued to do so for the next few months that the patient 
was under observation. 

Case VIII. Corneal astigmatism with the rule, 1 Z>., with 
no lenticular astigmatism; Presbyopia. — Mrs. T. R., aged 
fifty-three, in moderately good health. She began to wear 
glasses seven years ago, but they have never given her com- 
fort, her eyes paining her when she sews or reads. 



i 



ILLUSTRATIVE CASES 

Ophthalmometer. — Astigmatism with the rule, 
90° + or 180° - in each eye. 
Test cai'ds and trial lenses. — 



1 D. 



53 



axis 



i^- ^- = H = ff W- + 1 i^- cyh, 90°. 

L. V. = IM^ W. + 1 D. cyl., 90°. 

Reads Jaeger No. 1 at 8 inches with + 3 D. spherical 
glass added for the presbyopia. + 3 D.s + 1 D. cyl., 90° was 
ordered for each eye for reading. These glasses have given 
her entire satisfaction for almost three years. 

The last four cases reported are somewhat out of the ordi- 
nary, because of the absence of lenticular astigmatism. Fur- 
thermore, they serve to show the necessity of testing for any 
astigmatism that the ophthalmometer indicates, for it may be the 
only form of astigmatism present. 

Case IX. Hypermetropic astigmatism against the rule^ 1 D. 
right ege, .75 D. left eye ; Patient accepts .50 D. more than the in- 
strument reads. — L. M.,i aged thirty-nine, general health good. 
Her eyes have not given her 
any special trouble until the 
last year, when they began 
to pain her and the vision to 
blur when she read or sewed 
for any great length of time. 
At night she had to give up 
close work and reading. 

Ophthalmometer. — Astig- 
matism against the rule, ID., 
axis 180° -F or 90° - right 
eye; .75 D., axis 180° -}- or 
90° -left eye. 

Figure 26 is a diagram- 
matic section of such an eye showing where the rays of light 

1 Reported from Drs. Lewis and Van Fleet's clinic. 




J 80 



Fig. 26. 



54 THE REFRACTION OF THE EYE 

focus respectively in the vertical and horizontal meridians. 
The horizontal meridian is emmetropic and focusses rays on 
the retina ; while the vertical meridian is hypermetropic, less 
curved than the horizontal, and allows the rays of light to 
focus back of the retina. 

Test cards and trial lenses. — The vertical lines on the 
Green's clock-dial are seen plainest. 

R. V. = f^ : fj + W. + 1.50 D. cyl., 180°. 
L. V. = 1^ : f^ + W. + 1.25 D. cyh, 180°. 

Ophthalmoscope. — Simple hypermetropic astigmatism against 
the rule. 

On a second test the same glasses were accepted by the 
patient and were ordered. The above glasses have been worn 
for three years with perfect satisfaction. Usually in cases of 
astigmatism against the rule we add .50 D. to the reading of 
the instrument. However, it may be more or less, as illus- 
trated by some of the following cases. Furthermore, in the 
cases of astigmatism against the rule must be reckoned those 
w^here there is no corneal astigmatism at all, for in such cases 
there is usually a small amount of lenticular astigmatism 
against the rule which must be corrected. 

Case X. Corneal astigmatism against the rule ; The patient 
accepts only .25 D. more than the instrume^it reads. — Lawrence 
M., aged eleven, was seen at the clinic on February 2, 1897. 
Is in good health, family history good — father died aged forty, 
from accident, mother living, aged thirty-three, one sister older 
and two brothers younger living — none ever wore glasses. 

Ophthalmometer. — Astigmatism against the rule, .25 D., 
axis 180° + or 90° - in each eye. 

Test cards and trial lenses. — 

R. V. = 11 : ff W. + .50 D. cyl., 180°. 
L. V. = f-l : ff W. + .50 D. cyl., 180°. 



ILLUSTRATIVE CASES 55 

Reads Jaeger No. 1 at 6 inches. 

Ophthalmoscope. — Hypermetropia 1 diopter in each eye. 

A mild astringent wash was ordered for the lids, which 
were somewhat inflamed. On a second test, one week later, the 
patient accepted the same glass as at first. Ordered + .50 D. 
cyl. 180° each eye. September, 1897, the glasses were still 
satisfactory. 

Case XI. Ophthalmometer shoivs corneal astigmatism against 
the rule., and the patient accepts .75 D. more than the instrument 
reads. — Abbie P., aged forty-six, came to the clinic on Decem- 
ber 27, 1892. Has worn glasses for the last six years, but none 
of them have been satisfactory. She is in fairly good health. 

Ophthalmometer. — Astigmatism against the rule, .25 D., 
axis 180° + or 90° — in each eye. 

Test cards and trial lenses. — 

R. V. = f ^ : 1^ + W. 1 D. cyl., 180°. 
L. V. = 1^ : 1^ 4- W. 1 D. cyl., 180°. 

Reads Jaeger No. 1 at 10 inches with a + 3 D. added for 
presbyopia, which is a big amount considering the age of the 
patient, only forty-six years. 

Ophthalmoscope. — Hypermetropic astigmatism. 

Two days later a second test gave the same result as the 
previous one. Ordered -f- 1 D. cyl., 180° each eye, for dis- 
tance ; and -J-3D.S added for reading. The same strength 
cylindrical glasses have been worn since, but the spherical part 
has been increased for the increasing presbyopia. 

Case XII. Ophthalmometer shoivs astigmatism against the 
rule; The patient accepts the reading of the instrument exactly 
in one eye., hut .25 D. less than the reading of the instrument 
in the other ^ though the astigmatism is against tlie rule. — S. H. 
W., aged thirty-six, in robust health, consulted me February 5, 
1894, on account of painful vision. His eyes have troublecj 
him more or less for over a year, especially for close work. 



^Q THE REFRACTION OF THE EYE 

Ophthalmometer. — Astigmatism' against the rule, 1.50 D., 
axis 180° -I- or 90° - right eye ; .75 D., axis 180° + or 90° - 
left eye. 

Test cards and trial lenses. ^ — 

R. V. = 3-%<L : f^ W. + 1.50 D. cyl., 180°. 
L-V. = 1^ :|^W. + .75 D. cyl., 180°. 

Reads Jaeger No. 1 at 5 inches. 

Ophthalmoscope. — Hypermetropic astigmatism against the 
rule, 1 D. each eye. 

On a second test the ophthalmometer gave the same reading, 
and the patient accepted exactly the same glass in the right 
eye, but a .25 D. weaker glass in the left eye. Ordered : — 

+ 1.50 D. cyl., 180° right eye ; 
+ .50 D. cyl., 180° left eye. 

May, 1896, over two years after they were ordered, the 
glasses were still giving entire satisfaction. 

Case XIII. No corneal astigmatism^ hut the patient accepts 
a -\- .50 D. cylindrical glass against the rule., at 180°. — C. C. 
D., aged forty-two years, general health is good. He consulted 
an eminent oculist ten years ago, who told him that he had no 
refractive error ; his eyes continued to trouble him more or 
less all the time. Nine months ago he had spherical glasses 
fitted on account of presbyopia, but they have been unsatis- 
factory. He consulted me first in February, 1893, when the 
following condition of affairs was found : — 

Ophthalmometer. — Shows no corneal astigmatism, that is, the 
images of the mires neither overlap nor separate at any position 
after they have once been approximated, and the black lines 
dividing them into halves remain opposite and straight in all 
positions. 

In such cases it is usual for the patient to have lenticular 



ILLUSTRATIVE CASES 



57 



astigmatism of about .50 D. against the rule, that is to say, if 
the eye is hypermetropic that a plus cylindrical glass will be 
worn with its axis at 180°, or in that neighborhood, while if 
myopic a minus cylindrical glass will be worn at 90°, or in 
that neighborhood. 

A and B in Fig. 27 show the shape of the cornea and lens 
respectively, and focuses of the two chief meridians combined in 
the present case. A shows both meridians of the cornea to 




Fig. 27. 



have the same radius of curvature, therefore the cornea to be 
spherical in shape. It is emmetropic in refractive power in 
this case. 

The lens (5, Fig. 27) is emmetropic in refractive power in 
the horizontal meridian also, but in the vertical meridian it is 
hypermetropic by .50 D. 

As both the cornea and the lens are emmetropic in the 
horizontal meridian, it allows the rays of light that pass through 
that meridian to focus exactly on the retina. The cornea is 
emmetropic in the vertical meridian also, but the lens is hyper- 
metropic .50 D., and consequently the rays of light that pass 



58 THE REFRACTION OF THE EYE 

through that meridian focus behind the retina. It requires a 
cylindrical glass of .50 D., axis 180°, to focus these rays of 
light on the retina ; and a plus cylindrical glass worn with its 
axis at 180° shows the astigmatism to be against the rule. 
Test cards and trial lenses. — 

R. y. = |o _ : 1| W. -f- .50 D. cyl., 180°. 

L. Y. =!-§--: fl W. + .50 D. cyl., 180°. 

Reads Jaeger No. 1 at 7 inches with a + .75 D. spherical 
glass added to correct the presbyopia. 

Ophthalmoscope. — Hypermetropic astigmatism .50 D. against 
the rule. 

Ordered + .75 D. + .50 D. cyl., 180° each. May, 1895, two 
years later, the glasses are still satisfactory. 

In such cases as the above, and especially in presbyopes, the 
retinoscope is of value in confirming the subjective tests. In 
young subjects, however, to make the retinoscopic tests reliable 
atropine or some mydriatic must be used, which fact impairs 
its usefulness very much. Fortunately it is seldom necessary 
to use mydriatics of any kind, and in my practice retinoscopy, 
or more correctly speaking, skiascopy., plays a very unimportant 
role. 

Case XIV. No corneal astigmatism. TKe patient accepts + 
cylindrical glasses against the rule at different axes, 180° and 135° 
respectively. — N. Y., aged fourteen years, general health first- 
class, consulted me April 1, 1896. For three months her eyes 
have troubled her greatly, and especially after studying her 
lessons. Blurring of the vision, pain in the eyes, and headaches 
are the chief symptoms she complains of. She has an older 
sister who has mixed astigmatism. 

Ophthalmometer. — No corneal astigmatism. 

Retinoscope. — Hypermetropic astigmatism of small amount 
(.50 D.) in each eye, axis of cylindrical glass 180° Rt., and at 
135° (?) Lft. 



ILLUSTRATIVE CASES 



59 



Test cards and trial lenses. — The vertical lines from XII to 
VI in the clock-dial are seen plainest in the right eye, while the 
lines from X to IV and XI to V are seen plainest with the left 
eye. 



R V — 2-^ 
JX. V . — 20 



L. V. 



:ff W. + .50D. cyl.,180°. 
|o _ . 10 w. + .50 D. cyL, 135°. 



Reads Jaeger No. 1 at 3 inches. 

Ophthalmoscope. — Hypermetropic astigmatism of small 
amount, but could not be estimated accurately. 

Figures 27 and 28 show the form of the cornea and the foci 
of the chief meridians in the right and left eyes respectively. 

On account of a mild 
conjunctivitis, an astrin- 
gent wash for the eyes was 
ordered, and the patient re- 
quested to come again in 
one week. A mydriatic was 
ordered to be used for three 
days before coming for the 
second test. The second 
test corresponded with the 
first as to the amount and 
axis of the astigmatism, but 
the patient accepted + . 75 
D. spherical glasses in ad- 
dition to the cylinders. The 
ophthalmoscope and retinoscope showed compound hyperme- 
tropic astigmatism. Ordered: — 

-K .50 D. cyl., 180°, right eye ; 
+ .50 D. cyl., 135°, left eye. 

One year later, April, 1897, the glasses were still entirely 
satisfactory. 




Fig. 28. — Astigmatism against the rule, 
with the axes at 45° and 135° (left eye) . 



60 THE REFRACTIOX OF THE EYE 

Case XV. Ophthalmoineter shows no corneal astigmatism ; 
Patient accepts a -f .25 D. cylindrical glass agamst the rule, axis 
180° in each eye. — Mary T., aged forty, came to the clinic 
March 10, 1895, for glasses for reading and sewing. The pa- 
tient is in good health. 

Ophthalmometer. — No corneal astigmatism whatever, the 
lines dividing the mires being straight with each other in all 
meridians, and the images neither overlapping nor separating 
after once being approximated. 

Retinoscopy was unsatisfactory, both as to the axis and the 
amount of the astigmatism, and even as to the kind. 

Test cards and trial lenses. — 

^' ^' = U '-U W- + -25 D. cyl., 180^ 
L. Y. = f§ : 1^ - W. + .25 D. cyl., 180°. 

Reads Jaeger No. 1 at 10 inches with a + 1 D. spherical 
glass added. 

Ophthalmoscope. — Emmetropic in each eye, apparently. 
The patient has a lachrymal catarrh, for which she was treated 
for three weeks before a second test was made. 

Second test : The ophthalmometer gave the same reading 
and the patient accepted the same glass as on the first test. 
Ordered : + 1 D.s -}- .25 D. cyl., 180° for each eye for reading. 

Case XVI. Ophthalmometer shows no corneal astigmatism ; 
The patient accepts -\- .15 D. cylindrical glass against the rule., 
axis 180° in each eye. — R. H. U., aged twenty-one, student, 
consulted me September 5, 1G93. The patient is in good health, 
but somewhat run down from hard study. He complains of 
pain in the eyes, blurring of vision after long work, and also 
of a slight discharge from, and stiffness of, the lids. 

Ophthalmometer . — No corneal astigmatism. 

Retinoscope. — .50 D. astigmatism against the rule, with the 
chief axes at 180° and 90° ? 



ILLUSTRATIVE CASES 61 

Test cards and trial lenses. — 

R. V. = 1^ - : 1^ + W. + .50 D. cyl., 180^ 
L. V. = |g - : 1^ + W. + .50 D. cyl., 180°. 

Reads Jaeger No. 1 at 5 inches. 

A mild astringent wash was prescribed for the conjuncti- 
T"itis. One week later a second test was made, the ophthal- 
mometer still read negative, but the patient accepted + .75 D. 
cylindrical glass, axis 180°, over each eye, which was ordered. 
Three years later these glasses were still satisfactory, but at 
times the patient was troubled with conjunctivitis and a slight 
discharge from the lids. 

Case XVII. No corneal and no lenticular astigmatism^ a 
"moderate amount of latent hypermetropia. — Miss R. G. L., aged 
twenty-three, consulted me October 24, 1896. She is in good 
health, but overworked in a " School of Applied Design," 
where she is trying to take a two years' course in one year's 
time, and as a consequence has overtaxed her eyes with fine 
drawing. For the past two weeks the left eye especially has 
pained her after working all day. 

Ophthalmometer. — No corneal astigmatism whatever. 

Test cards and trial lenses. — 

R. V. = 11^ : not improved with any glass. 
L. y . = \^ : not improved with any glass. 

Reads Jaeger No. 1 from 3|- to 20 inches. 

Ophthalmoscope. — Hypermetropia 1.25 D. both. 

No muscular insufficiencies present. 

This patient was ordered to discontinue some of her work, 
was put on tonics, and in a few weeks' time had no further 
trouble. 

Contrary to the above case (that is, no corneal astigma- 



62 THE REFRACTION OF THE EYE 

tism), we usually have .50 D. of lenticular astigmatism against 
the rule when there is no corneal astigmatism present. 

Case XVIII. Astigmatism with the rule^ .25 D.^ axis 90° -f- 
(?rl80°— , according to the ophthalmometer; Patient accepts a 
+ .25D. cylindrical glass., axis 180°, against the rule. — Annie 
D., aged twenty-scTen, in good health. She came to the clinic 
at the Manhattan Eye and Ear Hospital on account of her eyes 
hurting when she did close work. 

Ophthalmometer. — Astigmatism with the rule, .25 D., axis 
90° + or 180° - in each eye. 

Test cards and trial lenses. — 

R. V. = 1^ : ff W. + .25 D. cyl., 180^ 
L. V. = 1^ : ff W. + .25 D. cyl., 180°. 

Reads Jaeger No. 1 at 6 inches. 

The test with the lines on the clock-dial was unsatisfactory^ 
as was also retinoscopy. 

Ophthalmometer. — Hypermetropia .50 D. each eye. 

A second test two days later gave the same result, and -f . 25 
D. cylindrical glass, axis 180°, was ordered for each eye. These 
glasses have given satisfaction for over a year. 

A second case similar to the above, that is, the patient 
accepting + .25 D. cylindrical glass against the rule (180°) when 
the ophthalmometer reads astigmatism with the rule .25 D., is 
furnished me b}^ Dr. Van Fleet from his private practice ; and 
I take this opportunity to express my thanks to him. I give 
the case as he reported it, with his remarks. 

Case XIX. Corneal astigmatism with the rule, .25 D. ; 
Patient accepts + .25 cylindrical glass against the rule and is 
relieved of a marked asthenopia., with marked improvement in 
vision. — ^' Miss P., aged nineteen years, has suffered for some 
time with headache, dizziness, occasional diplopia, and attacks of 
momentary blindness. In November, 1896, while looking out 



ILLUSTRATIVE CASES 63 

of a window at a passing parade everything suddenly appeared 
black to her, and she called to her sister who was in the room 
with her that she could not see. She felt sick and faint, and 
her family became alarmed and sent for the family physician, 
who responded at once, but by the time he arrived the attack 
had passed away. 

" The physician, fearing some kidney trouble, examined his 
patient very carefully, but was unable to discover anything 
abnormal about her. During the two weeks he observed her 
she had several of these attacks, and finally concluding her 
eyes must be at fault, he referred her to me for examination. 

"December 2, 1896. Patient is a large, healthy looking 
young woman, giving history as above. 

" Pupils normal and react properly. No apparent deviation 
of visual lines. 

" Ophthalmometer. — 0.25 D. with the rule. 

" Ophthalmoscope, about emmetropic. 

" Vision, both eyes |^ : |^ - with + 0.25 D. cyl. ax. 180°. 

" Reads J. 1 with and without this glass and has good range 
of accommodation. 

" Ordered : + 0.25 D. cyl. ax. 180° constant. 

"April 1, 1897. Physician reports that the patient is en- 
tirely free from all the asthenopic symptoms she formerly had. 

^'•Remarks. — The history is peculiar for two reasons : first, 
it \s unusual for such marked symptoms to result from so small 
a refractive error ; and second, it is unusual to have so great a 
diminution in vision made perfect with so weak a plus glass. 

" It exemplifies also the value of Javal ophthalmometer and 
the almost constant relation between the amounts of corneal 
and lenticular astigmatism. 

" One half diopter of corneal astigmatism with the rule 
being normal necessitates the existence of one half diopter of 
lenticular astigmatism against the rule. 

" The existence of one diopter with the rule in the cornea 



64 THE REFRACTION OF THE EYE 

indicates an excess of one half diopter which must be corrected. 
Obversely, a total absence of corneal astigmatism leaves un- 
corrected one half diopter lenticular astigmatism, necessitating 
a glass of one half diopter against the rule. 

" Therefore a quarter diopter of corneal astigmatism with 
the rule will correct one-half the normal lenticular astigmatism, 
necessitating one quarter diopter against the rule for complete 
correction." 

The chief thing of interest in these last two cases, from the 
point of view of the ophthalmometer, is that the patients should 
wear a .25 D. cylindrical glass against the rule when the 
instruments reads .25 D. astigmatism with the rule. Its ex- 
planation is easy, if we only keep in mind the rule to deduct 
.50 D. from the reading of the instrument when the astig- 
matism is with the rule. In the above cases there is only 
.25 D. of corneal astigmatism, consequently if the lenticular 
astigmatism is of the usual amount (.50 D.), it will not only 
neutralize the .25 D. of corneal astigmatism, but leave .25 D. 
of its own, or lenticular, astigmatism to be corrected. But 
why does this remaining .25 D. of lenticular astigmatism re- 
quire the cylindrical glass to be worn against the rule ? This 
can be explained better by diagrams than in any other way. 
^, Fig. 29, shows the cornea, front view, and the points where 
the rays of light passing through its two chief meridians would 
focus if no lenticular astigmatism was present ; B shows the 
lens, front view, and where the rays of light would focus after 
passing through its two chief meridians if no corneal astig- 
matism was present ; and C represents a composite of the two as 
they actually are and the points where rays of light focus after 
passing through the two chief meridians of each. 

The horizontal meridians of both the cornea and the lens in 
the above cases are emmetropic, as seen by the diagrams, and 
allow the rays of light to focus on the retina. The vertical 
meridian of the cornea is more curved by .25 D. than its 



VARIATION IN AXIS OF THE ASTIGMATISM 



65 



horizontal meridian. This is demonstrated by the overlapping 
of the images of the mires to the extent of .25 D. when they 
are turned from the horizontal to the vertical meridian after 
having been approximated. But the vertical meridian of the 
lens is too little curved by .50 D. It therefore neutralizes the 
.25 D. of corneal astigmatism (which is with the rule) and 
leaves still .25 D. lenticular astigmatism against the rule in the 
vertical meridian to be corrected, which requires + .25 D. 
cylindrical glass axis 180°. 



180 
CORNEA 




Fig. 29. — A shows the focuses of the two chief meridians of the cornea, assuming no 
lenticular astigmatism; B, the focuses of the two chief meridians of the lens, 
assuming no corneal astigmatism ; C, the focuses of their combined action, with 
.25 D. corneal astigmatism with the rule and .50 D. of lenticular astigmatism 
against the rule. 

Oases showing the variation of axes of the chief meridians of 
curvature of the cornea from 90° a7id 1S0°. — The plurality of 
cases of astigmatism have their chief meridians exactl}^ at 90° 
and 180°, and, as a rale, the meridian that has a shorter radius 
of curvature is at 90°, while the meridian that has the longer 
radius of curvature is at 180°. Many times the two chief 
meridians are not exactly at 90°, but vary ; and this variation 
in the majority of cases is symmetrical in character. ^ That is, 

1 Clairborne, JV. Y. Med. Jour. June 25, and July 2, 1892. See also refer- 
ence on page 200. 



66 



THE REFRACTION OF THE EYE 





R. E. 



L. E, 



Fig. 30. 



in cases of astigmatism with the rule, the shorter curved merid- 
ians slant the same number of degrees to the temporal, or nasal, 

side of 90° in each 
eye, while the longer 
curved meridians re- 
main at right angles 
to the shorter curved 
meridians. For exam- 
ple, if the shorter 
curved meridian in the right eye is at 75°, that is 15° to the 
nasal side of 90°, the shorter curved meridian in the left eye is 
at 105°, or also 15° to the nasal side of 90°. In other words, 
both axes slant inward to the extent of 15° (see Fig. 30). 

On the contrary, usually, if the shorter curved meridian in 
the right eye slants toward the temple 30°, the shorter meridian 
in the left eye slants toward 
the temple 30°. In such a 
case, the axis in the right eye 
would be at 120° and in the 
left eve at 60°, with the 




eye 
longer curved meridians re- 




R. E. 



L. E. 



Fig. 31. 



spectively at right angles (see 
Fig. 31). In such a case, if the patient was hypermetropic, 
plus cylinders would be worn at 120° and 60° ; if myopic, 
minus cylinders at 30° and 150°. 

There are a number of exceptions to this rule, however. 
For instance, the meridian of shorter radius of curvature may 
slant but 10° to the temporal side of the vertical meridian in 
one eye and 15° to the temporal side in the other, etc. Or, 
again, the two chief meridians of curvature may be exactly at 
90° and 180° in one eye, while the chief meridians may be 
slanting in the opposite eye ; and so on. 

At rare intervals, the shorter curved meridian in each eye 
may slant in the same direction from the vertical meridian, that 



ILLUSTRATIVE CASES 



61 





135 



is, to the temple in one eye and to the nose in the other. For 
example, both of the shorter curved meridians may be at 75° 
(see Fig. 32). 

In astigmatism against the rule the longer curved meridian 
is at 90° or its neighborhood, and is subject to the same variations 
as in the case of astigma- 
tism with the rule. les/^ !/ X les 

In exceptional cases, 
the two chief meridians 
of curvature stand ex- R- E. L. E. 

"Ftp S9 

actly at 45° and 135°. If ' 

this happens in both eyes, the meridian of the shorter radius of 
curvature is usually at 45° in one eye and at 135° in the other. 

The symmetry of the eyes, as 
indicated in the beginning of 
,:this section, is thus carried out. 
For each shorter meridian in 
L. E. this instance would slant the 

same number of degrees from 
the vertical, and both either toward the temples, or both 
toward the nose (see Fig. 33). 

In all of these cases, the ophthalmometer is of inestimable 
value in finding the axes, and no method compares with it for 
accuracy and facility. 

Case XX. Both axes slant 30° to the nasal side of the 
vertical meridian^ standing at 60° in the right eye and at 120° in 
the left eye. — Agnes R., aged twenty-seven, consulted me 
July 9, 1895. She had worn glasses for a year, but without 
relief of her eye symptoms, which were pain, blurring of 
vision, headaches, etc., in fact, typical asthenopia. 

Ophthalmometer. — Astigmatism with the rule, ID., axis 

60° + or 150° - right eye ; 1 D., axis 120° -f- or 30° - left eye. 

In the present case, in the right eye, the black lines dividing 

the mires were not straight at 0°, but were at 150°, and that 





Fig. 33. 



68 



THE REFRACTION OF THE EYE 



was the starting point or primary position. The mires were 
approximated, and the long indicator turned at right angles ta 
the primary position or to 60°, where they overlapped one step. 
This was, therefore, astigmatism 1 D. with the rule, axis 60° + 
or 150°-. 

In the left eye the primary position was found at 30°, and 
the secondary position at 120°. 

Test cards and trial lenses. — 

^•^•=M-MW. +.50D. cyL, 60°. 
L. V. = II : ff W. + .50 D. cyl., 120°. 

Reads Jaeger No. 1 at 6 inches. 

Ophthalmoscope. — Hypermetropic astigmatism in each eye^ 



150 




R. E. 




Fig. 34. 



On the second test the patient accepted the same glass as at 
first. Ordered : — 

+ .50 D. cyl., ax. .60° right; 

-h.50D. cyL,ax. 120° left. 

Case XXI. Both of the shorter axes slant 15° to the tem- 
poral side of the vertical meridian., standing at 105° in the right 



ILLUSTRATIVE CASES 



69 



eye and at 75° in the left eye, — Hannah M., aged thirty, con- 
sulted me January 23, 1897. She complained that the eyelids 
became red and swollen at times, and of frontal headaches and 
pains in the eyeballs. Her general health is good. 

Ophthalmometer. — Astigmatism with the rule, 1 D., 105° 
+ or 15° - right eye ; 1.50 D., 75° + or 165° - left eye. 




R. E 



Fig. 35. 

Test cards and trial lenses. — 



L.E, 



I^-^-f*- -I^W. + .50D. cyl.,105°. 

L.V.f-J-:|aW. +1 D. cyl., 75°. 

Reads Jaeger No. 1 at 7 inches. 

Ophthalmoscope. — Hypermetropic astigmatism with the rule. 

A second test resulted the same as the first. Ordered : — 

+ .50 D. cyl., 105° right eye ; 
4-1 D. cyl., 75° left eye. 

Yellow oxide of mercury ointment was prescribed for the 
redness of the edges of the lids. 



70 



THE REFRACTION OF THE EYE 



June, 1897. The patient has worn the glasses with perfect 
comfort, and the blepharitis marginalis has been relieved. 

Case XXII. Both axes slant hut 5° to the temporal side of 
the vertical meridian^ standing at 95° in the right eye and at 85° 
in the left eye. — Miss F. J. O., aged twenty, consulted me 
March 27, 1897. For two years she has been troubled by 
shadows whirling around in front of her eyes. These shadows 
are not constant, but appear at intervals and are annoying to 
the patient. She has no headache and no pain in the eyes. 




R. E. 



L. E. 



Fig. 36. 



Ophthalmometer. — Astigmatism with the rule, 1.50 D., axis 
95° + or 5° - right eye ; 1 D., axis 85° + or 175° - left eye. 

The primary position was found at 5° and the secondary at 
95° in the right eye. The primary position was found at 175** 
and the secondary at 85° in the left eye. 

It will be noticed that in most cases of astigmatism with 
"off" axes, that is, with the axes away from 90° and 180°, the 
secondary position can be obtained by adding 90° to the primary 
position when that is less than 90°, and by subtracting 90° from 



ILLUSTRATIVE CASES 71 

the primary position when it is less than 90°. For instance, in 
this case the primary position in the right eye is at 5°, add 90° 
to it, and we get 95°, the secondary position. In the left eye 
the primary position is at 175°, subtract 90° from it, and we get 
85°, the secondary position. This is true in all cases when the 
chief meridians are at right angles to each other, and they 
usually are. 

Test cards and trial lenses. — 

R. y. = 1^ - : 1^ W. + 1 D. cyl., 95°. 
L. V. = f J - : 20 w. + 1 D. cyl., 85^ 

Reads Jaeger No. 1 at 4 inches. 

Ophthalmoscope. — Simple hypermetropic astigmatism with 
the rule. 

March 30, three days later, the ophthalmometer reads the 
same : — 

R. V. = 1^ - : f ^ W. + 1 D. cyl., 95°. 
L. V. = f^ - : 1^ W. + .75 D. cyl., 85°. 

Ordered : — 

+ 1 D. cyl., 95° right; 

+ .75D. cyL,85°left. 

Two months later the glasses were satisfactory. 

Case XXIII. Axis vertical or 90° in one eye^ and 15° from 
the vertical in the other eye., standing at 75°. — Robert I., aged 
fifteen, consulted me October 12, 1895. He suffered from a 
typical asthenopia and a mild conjunctivitis. He is in good 
general health, but a close student. 

Ophthalmometer. — Astigmatism with the rule 1 D., axis 75° 
+ or 165° - right eye ; 2.50 D., axis 90° + or 180° - left eye. 

The primary position in the right eye was found at 165° and 
the secondary at 75°. The primary position in the left eye was 
found at 0° or 180° and the secondary at 90°. 



72 



THE REFRACTION OF THE EYE 



165 




B,E. 



L.E. 



Fig. 37. 



Test cards and trial 



R.Y. = 2^_:|^W.+ .75D.,cyl.,75°. 
L. V. = f^ - : 1^ W. + 2 D., cyl., 90^ 

Reads Jaeger No. 1 at 5 inches. 

Ophthalmoscope. — Simple hypermetropic astigmatism with 
the rule in each eye. 

A mild astringent wash was ordered for the conjunctivitis, 
and the above glasses ordered : — 

+ .T5D.,cyl., 75°right; 
+ 2 D.,cyl.,90°left. 

May 1, 1896, the glasses were still satisfactory. 

Case XXIV. Both axes slant 15° in the same direction from 
the vertical meridian., to the temporal side in the right and to the 
nasal side in the left., standing in each at 105°. — R. E. P., 
aged thirty-seven, consulted me November 8, 1896, complaining 
of frontal headaches and pains in the eyes after reading or 



ILLUSTRATIVE CASES 



T3 



working. His general health is not very good, is a business 
man and overworked. 

Ophthalmometer. — Astigmatism with the rule ID., axis 
105° 4- or 15° — in each eye. The primary position in each 
instance was found at 15° and the secondary at 105°. 

Test cards and trial lenses. — 



R. Y. = 1^ _ : II W. -f- .50 D. cyl., 105°. 
L. V. = 1^ - : ff W. + .50 D. cyL, 105°. 

Reads Jaeger No. 1 at 
T inches. 

Ophthalmoscope. — Sim- 
ple hypermetropic astig- 
matism in each eye. 

On a second test the 
patient accepted the same 
glasses as at first. Or- 
dered : + .50 D. cyl., 105°, 
each eye. These glasses 
have continued to give 
comfort for six months, 
May 2, 1897, when the 
patient was last heard 
from. 

Case XXV. Astigmatism against the rule ivhere the axes of 
the glasses slant relatively the same number of degrees from the 
horizontal meridian^ standing at 15° in one eye and at 165° in the 
other eye. — In hypermetropic astigmatism against the rule and 
myopic astigmatism with the rule, when the axes vary from 90° 
and 180°, they usually slant the same number of degrees and 
relatively in the same direction from the horizontal meridian. 
However, there are exceptions just as numerous as the varia- 
tions noted in the cases of hypermetropic astigmatism with the 




Fig. 38. 



74 



THE REFRACTIOX OF THE EYE 



rule, above reported, and myopic astigmatism against the rule, 
to be reported, in regard to the vertical meridian. 

Mrs. N. E. R., aged thirty-nine, consulted me March 2, 
1897. She had worn glasses for a year, but her eyes continued 
to pain her when she did any near work. Frontal headaches, 
dizziness, and a drawing sensation in the eyes are the symptoms 
most complained of. 

Ophthalmometer. — Astigmatism against the rule, .50 D., 
axis 15° -h or 105° - right eye ; .25 D., axis 165° + or 75° - left 
eye. 




R. E. 



L. E, 



Fig. 39. 



The primary position in the right eye was found at 15°, 
the images of the mires approximated and the long indicator 
turned to 105° when the images separated ; the images were 
again approximated and the long indicator turned back to 15°, 
the primary position, when an overlapping of one-half a step 
took place. In astigmatism against the rule it is after this 
second turning that the axes and the amount of astigmatism 
are read off, the long indicator always showing where the 
plus glass will be worn if hypermetropia is present and the 



ILLUSTRATIVE CASES 75 

short indicators where the minus glass will be worn if myopia 
is present. 

In the left eye the primary position was found at 165°, the 
secondary at 75° where the images separated. The images 
were again approximated and turned back to the primary 
position, when an overlapping of a quarter of a step took place, 
reading, therefore, astigmatism against the rule, .25 D., axis 
165° 4- or 75°-. 

Test cards and trial lenses. — 

K. V. = 1^ - : f ^ + W. + 1 D. cyl., 15°. 

L. V. = |-^ - : 12- + W. + .50 D. cyl., 165°. 

Reads Jaeger No. 1 at 8 inches. 

Ophthalmo scope, — Simple hypermetropic astigmatism against 
the rule each eye. Ordered : — 

+ 1 D. cyl., 15° right eye ; 
+ .50 D. cyl., 165° left eye. 

Case XXVI. Astigmatism with axes at 45° and 135°. — 
Annie D., aged 14, was examined by me at the clinic July 10, 
1894. She was in good health, but suffered constantly from 
her eyes, more when she used them for close work. In fact, it 
was a typical case of asthenopia. 

Ophthalmometer. — Astigmatism with the rule, 2 D., axis 45° 
+ or 135° — right eye ; astigmatism against the rule, 2D., 
axis 135° + or 45° - left eye. 

Perhaps it is well here again to refer to the fact that Avhen 
the two chief meridians of curvature fall exactly at 45° and 135°, 
just halfway between the vertical and horizontal meridians, 
that, strictly speaking, we do not have astigmatism with or 
against the rule. But for the sake of uniformity of reading of 



76 



THE REFRACTION OF THE EYE 



the instrument we speak of these cases as being with and 
against the rule, just as in other cases. 

Furthermore, to make the reading of the instrument uniform, 
we have assumed one or the other of the meridians, either 45° 
or 135°, always as the primary position or starting point. For 
myself I always take 135° as the primary position in such cases. 
Starting with 135° as the primary position and turning the 
long indicator to 45°, that is at right angles, if the mires over- 




R. E. 



L. E. 



Fig. 40. 



lap we call the astigmatism with the rule, just as at other times 
when the mires overlap ; and if the mires separate when we 
reach 45° we call it astigmatism against the rule, approximate 
the mires a second time, and turn back to the primary -position 
at 135° to get the amount of overlapping. 

It must be remembered, too, in these cases with the axes at 
45° and 135°, that the subtraction of .50 D. from the reading 
of the instrument when the astigmatism is with the rule and 
the addition of .50 D. to the reading when it is against the 
rule does not always hold. 



ILLUSTKATIVE CASES 



7T 



In the present case in the right eye the lines dividing the 
mires became straight with each other at 135° (primary position) ; 
the images of the mires were then approximated and turned to 
45° (secondary position), when two steps of overlapping took 
place ; astigmatism with the rule, 2 D., axis 45° + or 135° — . 
In the left eye the primary position was also found at 135°, the 
images of the mires approximated, and the long indicator turned 
to 45° (second position), when the images of the mires separated. 
The images were again approximated, and the long indicator 
turned back to the primary position at 135°, when they over- 
lapped two steps; astigmatism against the rule, 2 D., axis 
135° + or 45° -. 

Test cards and trial lewises. — 



-^- ^ • 50 



2_0 W I 2 
3 ^^ ' ^ ^ 



^•^- =M-I^W. + 1.50D. cyl., 45°. 

D. cyl.,135°. 

Reads Jaeger No. 1 at 5 inches. 

Ophthalmoscope. — Simple hypermetropic astigmatism. 
July 8, second test was given and the patient accepted the 
same glass. Ordered : — 

+ 1.50 D. cyl., 45° right eye ; 
+ 2 D. cyl., 135° left eye. 

The lines on Green's clock-dial from I to YII and from II to 
VIII were seen plainest with the right eye ; and the lines from 
X to IV and from XI to V in the left eye. 

The reason that the patient saw two sets of lines plainly in 
each eye is that there are no lines on Green's dial corresponding 
exactly to 45° and 135°. The lines on the clock-dial correspond 
to 0° or 180°, 30°, 60°, 90°, 120°, and 150°. As a consequence 
there are two sets of lines equidistant on either side of 45°, and 
two sets equidistant on either side of 135°, seen equally plainly 
when the axes happen to be exactly at 45° and 135°. A glance 
at the clock-dial will quickly show how this is. Perhaps a better 



78 



THE REFRACTION OF THE EYE 



set of lines are those of Snellen, fan-shaped, which are much 
closer together than those on Green's clock-dial, corresponding- 
at least to every fifteen degrees. 

I may say here by way of explanation of the principle of 
Green's clock-dial arrangement of lines, that when the horizon- 
tal lines are seen plainest, assuming no spasm of accommoda- 
tion to be present, the presence of one of six conditions of 
error of refraction is indicated : (1) a simple hypermetropic 
astigmatism, (2) a compound hypermetropic astigmatism, (3) a 
mixed astigmatism with the hypermetropic portion greater than 
the myopic portion, all with the rule ; or (4) a simple myopic 
astigmatism, (5) a compound myopic astigmatism, (6) a mixed 
astigmatism with the myopic portion greater than the hyper- 
metropic portion, all against the rule. A glance at Figs. 9, 
10, 13, 16, 17, 18, in Chapter II, will show this, the lines that 
are seen plainest always corresponding with the meridian of 
greatest error of refraction. 

The horizontal meridian in all of the above cases is the one 
most at error, while the vertical is emmetropic or more nearly 
so than the horizontal in all of them. As the horizontal lines 
on the clock-dial are seen by means of the rays of light that 

pass through the vertical 
meridian of the cornea, it 
follows as a consequence 
that the horizontal lines 
on the dial will be seen 
plainest in the above cases. 
This is based on a simple 
principle of optics. We 
see lines by means of rays 
of light that light them 
up from side to side (a, a\ Fig. 41), and not by the rays of 
light that strike them in their horizontal or longitudinal direc- 
tion (b, b', Fig. 41). 



{!> Cb a OL a 



Fig. 41. — Showing how lines are seen by rays 
of light that strike them from side to side, 
a, a', and not by rays that strike them at 
their ends, 6, b'. 



GREEN'S CLOCK-DIAL 



79 



On the other hand, had the vertical lines been seen plainest, 
this would have indicated one of six other conditions, to wit : 
(1) Simple myopic astigmatism, (2) com- 
pound myopic astigmatism, (3) mixed 
astigmatism with the myopic portion 
greater than the hypermetropic, all with 
the rule ; or (4) simple hypermetropic 
astigmatism, (5) compound hyperme- 
tropic astigmatism, (6) mixed astigmatism 
with the hypermetropic portion greater 
than the myopic portion, all against the 
rule. 

The horizontal meridian is emmetropic 
or more nearly so than the vertical in all 

T . rm p 1 -1 ^^^- ^- — Showing how 

six conditions. Therefore the vertical vertical lines are seen 

lines on the clock-dial will be seen plain- ^y ^^y^ «* ^^s^^' «> 

^T^- Act\ ^'' *^^* Strike them 

est (J^lg. 42). from side to Side. 





T) 








Uj 














' 


















a. 




— a 




b' 





CHAPTER lY 

COMPOUND HYPERMETROPIC ASTIGMATISM — ILLUSTRATIVE 
CASES — SPASM OF ACCOMMODATION 

In compound hypermetropic astigmatism the ophthalmom- 
eter is used in exactly the same way as in simple hypermetropic 
astigmatism ; or, for that matter, as in every form of astigma- 
tism, that is, to find the position of the two principal meridians 
of curvature of the cornea and the amount of the astigmatism. 
These points once obtained, the character of the error of refrac- 
tion, if hypermetropic or myopic, is, in the great majority of 
cases, easily found out with the aid of the trial case, aided by 
the ophthalmoscope and other objective tests. In exceptional 
cases a mydriatic has to be called into requisition before a 
satisfactory glass can be prescribed, but such cases are very 
rare, as shown in the preceding chapter. 

Here again I wish to emphasize the importance of correcting 
the astigmatism first ; for if there happens to be only a simple 
astigmatism present, we have gone to the root of the trouble at 
once ; and if a spherical error is present in addition to the 
astigmatism, we have disposed of the astigmatism and have 
only the spherical error left to deal with, as in simple hyper- 
metropia and myopia. This method of procedure is of great 
advantage when there is a tendency to spasm of accommodation : 
for, after the astigmatism has been corrected in each eye 
separately, we can then put spherical glasses before both eyes 
at once. In this way, as is well known, the tendency to spasm 
of accommodation is overcome, and the patient many times 
accepts stronger plus, or weaker minus, glasses than when one 

80 



COMPOUND HYPERMETROPIC ASTIGMATISM 81 

eye is tested at a time. However, it should not be forgotten 
that spherical glasses should be tried in addition to the cylindri- 
cal glasses on each eye separately, before both eyes are tried 
together, for there may be more spherical error in one eye than 
the other. For example, say the patient accepts in the right 
eye + 1 D. -j- 2 D. cyl., 90°, and in the left eye + .50 D. + 
2 D. cyl., 90°, when each eye is tested separately. If we 
suspect spasm of accommodation, we should leave the cylin- 
drical glasses as they are and place in front of them at the 
same time a + .25 D. stronger spherical glass than they accepted 
singly. In this instance, in front of the right eye + 1.25 D. 
and in front of the left + .75 D. If these are accepted, add + 
.25 D, stronger sphere yet, and continue till the vision begins to 
be made worse. Where the patient does not accept as strong 
a cylindrical glass as indicated by the ophthalmometer, I often 
try both eyes at the same time with cylindrical glasses. Of 
course, this is after the eyes have been tried separately, when 
both cylindrical glasses can be increased proportionately in 
strength, just as in the case of spherical glasses. 

In compound hypermetropic astigmatism, spasm of accom- 
modation is more often present perhaps than in any other form 
of error of refraction. I have already shown in Chapter III, 
page 42 et sequiter, how it may be avoided if the test is begun 
and conducted properly. In the latter part of this chapter I 
treat of it in detail, — its causes, signs of its presence, and how 
to overcome it in most cases without the unnecessary use of 
mydriatics, together with illustrative cases. In this way I 
hope to show that this bugbear of refraction is not so much to 
be dreaded after all, and that a mydriatic is not the only Aveapon 
it can be fought with, though occasionally it has to be called 
into requisition as a last resort. 

I am not among those who believe in the use of the milder 
mydriatics, such as homatropine, because I believe when a 
mydriatic is needed, it is needed, and I use an efficient one 



82 THE REFRACTION OF THE EYE 

when I do use one, which is seldom. The two that I rely upon 
are atropine and scopolamine. The atropine is used in 4 grains 
to 5 1 solution for adults and half that strength for children, 
one drop being instilled into each eye three times a day for 
three days, after which the test is made. Then a week is 
allowed to elapse for the effects to wear off, Avhen another test 
is made, and usually the glass that the patient accepts on this 
last test is given. For, while it will not be so strong a glass as 
the patient accepted under the atropine, yet it will be stronger 
than the glass that was accepted before the mydriatic was 
instilled, because the week's enforced rest under the mydriatic 
has left the eye quiet and relieved the spasm of accommodation. 
However, should the glasses accepted on this last test not be 
strong enough, as compared by the glasses accepted while under 
the influence of the mydriatic, a large amount of latent hyper- 
metropia being present, I correct part of this latent hyperme- 
tropia (one-half to two-thirds of it) in addition to the manifest 
hypermetropia. 

Patients when given atropine to take home with them to be 
instilled into the eyes should be cautioned as to its poisonous 
effects at times, especially in children. Any flushing of the 
face or dryness of the throat should be the sign to stop its use. 

Scopolamine hydrobromid, 1 gr. to §i solution for adults 
and half that strength for children, is a very efficient and quick 
mydriatic. It is to be instilled into the eye of the patient by 
the doctor in the office, one drop in each eye every five minutes 
for thirty minutes, having the patient press his fingers over the 
tear-sac at the inner canthus of each eye all the while, so that 
none of the solution goes into the nose. Then have the patient 
wait for thirty minutes (one hour in all) before the test is 
begun. 

The advantages of scopolamine over atropine are : (1) that 
it is more powerful ; (2) it acts quicker, getting the patient 
ready for testing in one hour's time ; (3) its effects disappear 



MYDRIATICS 83 

more rapidly, lasting only from two to five days, while the 
effects of atropine last a week to ten days. Some few cases of 
poisoning have been reported from its use in the eyes,^ the 
toxic symptoms — rapidity of the pulse, flushing of the face, 
dryness of the throat, dizziness, at times nausea, and, in extreme 
, cases, delirium — being alarming in some cases. In most of the 
cases of poisoning reported, either the precaution of pressing 
on the tear-sac was not observed or the drug was used too 
freely. Just as with atropine, some cases are much more 
susceptible to it than others, hence it should be used with 
caution. However, with proper precaution it can be used with 
safety. 

Amblyopia, which is often present in high degrees of com- 
pound hypermetropic astigmatism, is often a stumbling-block 
for beginners, on account of which they often use a mydriatic 
when none is called for. In such cases, not being able to 
improve the vision much with any glass, they think perhaps it 
is their own fault in not fitting the glasses correctly that the 
patient does not obtain better vision, not stopping to consider 
that amblyopia may be present, and that no glass whatever will 
give better vision. They accordingly use a mydriatic, but find 
after all that the patient cannot be made to see any better 
ivith the glasses accepted under the use of a mydriatic than with 
those accepted at first. They have simply had their trouble 
lor nothing besides giving the patient great inconvenience. 

My own practice in such cases is to give two tests on 
different days. If the second test corresponds with the first, I 
order the glasses that are accepted though they do not improve 
the vision much. By the use of the ophthalmometer we know 
if any corneal astigmatism is present or not, and, if present, its 
axis and amount. With this important point ascertained we 
know approximately beforehand what cylindrical glass the 

1 Pooley, Foster, and Smith, among others, in this country, while several 
•cases have been reported abroad. 



84 THE REFRACTION OF THE EYE 

patient should accept and do not have to depend so much on 
his answers. After the astigmatism is once corrected, the 
spherical part of the error is corrected with comparative ease. 
Of course, if the two tests do not agree, and if there is a ques- 
tion of spasm of accommodation, I do not hesitate to use a 
mydriatic, and a strong one. After a mydriatic has been em- 
ployed, retinoscopy may be brought to the aid of the other tests. 
But without the use of a mydriatic I have not found retinoscopy 
satisfactory ; for that reason I rarely employ retinoscopy in my 
practice, since I use mydriatics so seldom. 

Some illustrative cases will serve to bring out the points I 
have mentioned above. 

Case XXVII. Ophthalmometer shotvs astigmatism tvith the 
rule, 1 D. ; Patient accepts compound plus 'glasses with relief of 
asthenopia and conjunctivitis. — Sophia F., aged twenty-four, 
in good health, complains that she has frequent headaches, 
and that her eyes ache after using them, also that the ej^elids 
itch and burn at times. 

Ophthalmometer. — Astigmatism with the rule, 1 D., axis 
90° + or 180° - in each e^^e. 

Test cards and trial 



R. V. = 1^ - : 1^ W. + .50 D. + .50 D. cyl., 90°. 
L. V. =1^- :f^ W. -f-.50D. +.50 D. cyl., 90°. 

Reads Jaeger No. 1 at 6 inches. 

Ophthalmoscope. — Hypermetropia in the vertical meridian 
1.50 D., and in the horizonal meridian 2 D., in each eye respec- 
tively. 

On account of a mild conjunctivitis, an astringent wash was 
ordered for the lids and the patient directed to return in two 
weeks. 

Second test : the ophthalmometer reads the same as at the 
first test. 



ILLUSTRATIVE CASES 85 

Test cards and trial lenses. — 

^'^'=i^'U W. + 1 D. + .50 D. cyl., 90°. 
L. V. = f^ : 1^ W. + 1 D. + .50 D. cyL, 90°. 

The ophthalmoscope showed about the same condition as on 
the first test. Tlie conjunctivitis is much improved. Ordered : 
+ 1D. +.50 D. cyl., 90° each eye. These glasses have been 
worn for more than four years with relief from her asthenopic 
symptoms. 

Case XXVIII. Large amount of astigmatism with the axis 
slanting relatively the same number of degrees from the vertical 
meridian., 15° to the nasal side^ in each eye ; Patient accepts a 
compound plus glass with relief of asthenopic symptoms. — March 
14, 1893, Mary D., aged twenty-four, in good health, but her 
eyes ache after she uses them for a short time for close work, 
especially in the evening. 

Ophthalmometer. — Astigmatism with the rule, 3 D., axis 
75° + or 165° - right eye ; 3 D., axis 105° + or 15° - left eye. 





R.E. • L.E. 

Fig. 43. 

Test cards and trial lenses. — • 

R. V. = f-J - : 2^ W. + 3 D. 4- 2.50 D. cyl., 75°. 
L. y. = II - : 1^ W. + 3 D. + 2.50 D. cyl., 105°. 

Reads Jaeger No. 1 at 6 inches. 

Ophthalmoscope. — Hypermetropia 3.50 D. at 75° and 6.50 
D. at 165° right eye; and 3.50 D. at 105° and 6.50 D. at 15° 
left eye. 



86 



THE REFRACTION OF THE EYE 



The lines on the clock-dial from II to VIII were seen best 
with the right eye, and from X to IV in the left eye. The 
simple cylindrical glass before each eye served to bring out all 
the lines on the clock-dial equally clear, indicating that the 
astigmatism had been corrected. On a second test the patient 
accepted exactly the same glass as on the first test, and it was 
ordered, and has been worn with comfort ever since. 

Case XXIX. Astigmatism against the rule, 1 D., with the 
axis 15° from the horizontal meridian in each eye; Patient accents 
compound plus glasses and gets relief from asthenopia. — May 11, 
1892, Mrs. C. W. T., aged thirty-nine, in good general health, 




B. E, 



L.E. 



Fig. 44. 



came for glasses on account of painful vision and headaches. 
The pupil in the left eye was dilated for some weeks when she 
was a child, from some unknown cause. She never had scarlet 
fever or diphtheria, or any serious illness. 

Ophthalmometer. — Astigmatism against the rule, ID., axis 
15° 4- or 105°- right eye; 1 D., axis 165° + or 75°- left 
eye. 



ILLUSTRATIVE CASES 87 

Test cards and trial lenses. — 

R. V. = If : ff W. + 1 D. + 1 D. cyl., 15^ 
L. V. = f^ : ff W. + .75 D. + 1 D. cyl., 165°. 

Reads Jaeger No. 1 at 8 inches. 

Ophthalmoscope. — R. 2.50 D. at 105° and 1.50 D. at 15°, 
right eye ; H. 2.50 D. at 75° and 1.50 D. at 165°, left eye. 

On a second test, three days later, the patient accepted 
exactly the same glass in the left eye and a quarter diopter 
weaker spherical glass in the right. Ordered : — 

+ .75 D. + 1 D. cyl., 15° right; 

+ .75 D. + 1 D. cyl., 165° left. 

These glasses have been worn for five years with comfort. 
However, as she is becoming presbyopic, she will soon have 
to wear stronger glasses for reading and close work. 

Case XXX. Small amount of astigmatism associated ivith 
a large amount of hyper metropia ; Marked asthenopia; Relief with 
glasses. — November 27, 1893, Miss M. H., aged thirty-five, in 
good health, came for glasses because her old glasses did not 
suit her. She has worn glasses for the last six years. The 
vision blurs after reading for a few moments, and she has to 
stop and rub the eyes before she can continue. 

Ophthalmometer. — Astigmatism with the rule, 1.25 D., 
axis 90° + or 180° - right eye ; 1.25 D., axis 105° + or 15° - 
left eye. 

Test cards and trial lenses. — 

^' ^' = 2% : I* W. + 4 D. + .75 D. cyl., 90°. 
R. L. = 2V0 • -I* W. + 4 D. + .75 D. cyl., 105°. 

Reads Jaeger No. 1 at 7|- inches. 

Ophthalmoscope. — H. 4 D. at 90° and 5 D. at 180° right 
eye ; H. 4 D. at 105° and 5 D. at 15° left eye. 



88 



THE REFRACTION OF THE EYE 



A second test resulted in the patient accepting exactly 
the same glass as at the first test, and it was ordered. They 
have been worn four years, with entire relief of asthenopia 
symptoms. 

The point of interest in this case, as far as fitting the 
glasses is concerned, is the order of sequence in which the 
glasses should be placed in the trial frames during the test. 
That is, if cylindrical glasses should be tried first, or spherical 




B. E. 



L. E, 



Fig. 45. 



glasses. In an article on the Technics of the Trial Case,^ I have 
stated it as a rule to be generally followed, that in cases of 
compound astigmatism it is always best to correct the astig- 
matism first, unless there is a large amount of spherical error 
present, — a hypermetropia of 6 D. or more, a myopia of 
8 D. or more, with only a small amount of astigmatism 
present. Perhaps in that statement I gave the amount of 
the spherical error too large in cases where it is necessary 
first to correct part of the spherical error before correcting 

1 iVeic York Med. Jour., June 20, 1896. 



ILLUSTRATIVE CASES 89 

the astigmatism ; for I have sometimes found it necessary in 
cases of hypermetropia of only 4 D., and in myopia of only 
6 D., with a small amount of astigmatism present, to correct 
part of the spherical error before the patient could appreciate 
the effect of a weak cylindrical glass when placed in front of 
the eye. In fact, in the present case, with 4 D. of hypermetro- 
pia and 1.25 D. of corneal astigmatism, part of the spherical 
error had to be corrected first before the cylindrical glasses 
could be appreciated. Usually, however, in cases of hyperme- 
tropia of 4 D. and less and myopia of 6 D. and less, compli- 
cated with an astigmatism of as much as 1 D., the cylindrical 
glass will be appreciated and vision improved to a slight 
extent with it alone, and before the spherical glass is added. 
The tendency in such cases, — large amount of spherical error 
associated with small amount of astigmatism, — where the 
cylindrical glasses are tried first, is for the patient to accept 
too strong cylindrical glasses. I am careful in such cases, at 
the close of the test, to weaken the cylindrical glasses slightly 
and at the same time to i«ncrease the strength of the spherical 
glasses a little, to see if the vision is improved by the change. 
If it is, I make the change ; if not, I give the original glass 
as first accepted. I mention this fact here for the benefit of 
beginners and because it is a point of practical importance. 
I may say, on the other hand, for those who make it a habit 
to correct the spherical error first, that the reverse condition 
holds ; that is, the patient is liable to accept too strong a spheri- 
cal glass relative to the cylindrical glass. In such case it is 
well to weaken the spherical glass at the close of the test and 
at the same time increase the strength of the cylindrical glass 
to find if vision can be improved. 

Again, in such cases as the one reported, the patient may 
accept the cylindrical glass as indicated by the ophthalmometer 
without either improving or making the vision worse. In 
such a case, leave the cylindrical glass on and proceed to cor- 



90 THE REFRACTION OF THE EYE 

rect the spherical error. When this is corrected, you will 
find that the vision is made worse if the cylindrical glass is 
removed, though while the cylindrical glass was on alone it 
seemed not to affect the vision one way or the other. This is 
easily accounted for. The spherical error being large, and the 
astigmatism being small, the cylindrical glass while on by 
itself has but little appreciable effect, but w^hen the spherical 
error is corrected (if there is not a marked amblyopia present), 
the vision is brought up to something like the normal, and the 
eye can then appreciate the presence or absence even of a weak 
cylindrical glass, which it could not do at first. 

Case XXXI. Hypermetropic astigynatism in each eye of 
equal amount^ 2 D. ; Patient accepts a simple plus cylindrical glass 
in 07ie eye, and a compound plus glass in the other; Relief from 
asthenopia. — May 9, 1893, Hannah D., aged twenty-five, has 
good general health, but has had weak eyes since a child. After 
any close work she has headaches and pains in the eyes, espe- 
cially the left eye. 

Ophthalmometer. — Astigmatism with the rule, 2 D,, axis 
75° + or 165° - right eye ; 2 D., axis 120° + or 30° - left eye. 

Test cards aiid trial lenses. — 

R. V. =f^- :f§W. -I-1.75D. cyl., 75°. 
L. V. = f ^ - : II W. + 1.50 D. cyl., 120°. 

Reads Jaeger No. 1 at 5J inches. 

Ophthalmoscope. — H. 2 D. at 165° and emmetropia at 
75° right eye; H. .50 D. at 120° and H. 2 D. at 30° left 
eye. 

Two days later a second test was made. The ophthalmom- 
eter read exactly the same, both as to the axis and amount 
of the astigmatism in the left eye as at the first test ; and 
the same axis, but .50 D. more in amount for the right 
eye. 



ILLUSTRATIVE CASES 

Test cards and trial lenses. — 

R. V. = li - : 1^- W. + 2 D. cyl., 75°. 

L. V. = f ^ - : 1^ W. + .50 D. + 1.50 D. cyL, 120< 

Reads Jaeger No. 1 at 51 inches. 



91 




R. E, 



L. E. 



Fig. 46. 



This last glass was ordered and has been worn constantly 
since, with relief from asthenopic symptoms. 

Case XXXII. Compound hypermetropic astigmatism agairist 
the rule iii one eye; Large amount of hypermetropia in the other 
eye ; Marked asthenopia ; Relief with the use of glasses. — 
December 17, 1895, Frances D. M., aged twenty-one, in poor 
general health, and is very nervous and easily excited or de- 
pressed. Her mother was a very nervous woman also. The 
patient suffers much from fatigue and often has headaches, 
and her eyes pain after any close work or reading. There is 
a mild conjunctivitis present. 

Ophthalmometer. — Astigmatism against the rule, .25 D., 
axis 30° + or 120° — right eye ; astigmatism with the rule, 
.50 D., axis 90° -f- or 180° - left eye. 



92 



THE REFRACTIOX OF THE EYE 



Test cards and trial lenses. — 

I^- ^- = t¥ • It W. + 3 D. + .75 D. cyL, 30°. 

Reads Jaeger No. 1 at 6 inches with the right eye, Jaeger 
No. 4 at the same distance with the left. 

Ophthalmoscope. —R, 4 D. at 120° and 3 D. at 30° right 
eye ; H. 7 D., left eye. 




R. E. 



L. E. 



Fig. 47. 



The second test resulted in the patient accepting the same 
glass as at the first test, and they were accordingly ordered. 
She has worn these glasses for eighteen months with great 
comfort, though at times she suffers from headaches when 
greatly exhausted. Her general health has improved con- 
siderably, but she is still easily excited. ^ 

The ophthalmometer in this case was of great service in 
pointing out the small amount of astigmatism against the rule, 
in the right eye, and also the small amount of astigmatism 

1 A note from the patient (June, 1898) informs me that she is still wearing 
the glasses with comfort, and that her health remains fairly good. 



ILLUSTRATIVE CASES 93 

with the rule, in the amblyopic left eye, which was neutralized 
by the lenticular astigmatism. In fact, had not the" ophthal- 
mometer been used in the case, it would have been necessary 
to have used a mydriatic in order to fit the correct glasses. 
This would have meant a week or ten days of widely dilated 
pupils, with much disturbance of vision, to an already excita- 
ble and nervous patient, and with no better nor even with as 
good result, as she had been fitted the year previously under a 
mydriatic with glasses that were not at all satisfactory. 

Case XXXIII. Compound hypermetropic astigmatism with the 
chief meridians of curvature at 45° and 135°; Marked asthenopia ; 
Relief with glasses. — February 25, 1894, Bertha F., aged thirty- 
nine, in good general health, has had "weak eyes" since a 
child. When thirteen years old she had "drops," salve, and 
glasses prescribed. She had but little trouble after that until 
eight years ago, when the eyes became painful, the eyelids red, 
and troublesome headaches followed, after using the eyes for 
close work. She again had salve, "drops," and glasses pre- 
scribed, but her eyes have continued painful and the lids red. 
She now has a well-marked blepharitis marginalis, and is fre- 
quently troubled with headaches. I ordered a mild astringent 
wash and yellow oxide of mercury ointment (2 grains to 3ii), 
and after two weeks made the first test for glasses. 

Ophthalmometer. — Astigmatism against the rule, 75 D., 
axis 135° -\- or 45° — right eye ; astigmatism with the rule, 
75 D., axis 45°+ or 135°- left eye. 

Test cards and trial lenses. — 

R. V. = ff - : ff W. + .75 D. + .25 D. cyl., 135°. 
L. V. = ff-: fl W. + 1 D. +.25D. cyl., 45°. 

Reads Jaeger No. 1 at 1^ inches. 

Ophthalmoscope. — Hypermetropia of 1.50 D. in each eye. 
It was impossible to estimate the small amount of astigmatism. 



94 



THE REFRACTION OF THE EYE 



Second test, three days later, resulted as follows : Oph- 
thalmometer gave the same reading as on the previous exami- 
nation. 

Test cards and trial lenses. — 

R. V. = fl - : ff W. + 1.25 D. + .25 D. cyl., 135°. 
L. V. = fl - : ff W. + 1.25 D. + .25 D. cyl., 45°. 




R. E. 



L. E. 



Fig. 48. 



The ophthalmoscope showed the same amount of H. as at 
the first examination. Ordered : — 

+ 1.25D. +.25D. cyl., 135°; 

+ 1.25D. + .25D. cyl., 45°. 

These glasses have been worn constantly for three and one- 
half years, and with entire relief of her blepharitis margin alis 
and freedom from asthenopia. Within a month a-|-.50D.s 
has been added to the distance glasses for reading purposes, 
on account of presbyopia, she being now 42^ years of age. 



ILLUSTEATIVE CASES 95 

Here again the ophthalmometer was of great assistance, 
for it pointed out the small amount of astigmatism that was 
present and at the unusual axes of 45° and 135°, — which 
astigmatism, by the way, had been overlooked at her previous 
tests under a mydriatic. The instrument read astigmatism 
against the rule in the right eye and with the rule in the left 
eye, and an equal amount in each, .75 D. In the right eye, 
instead of adding .50 D. to the reading of the instrument, as 
is usual in cases of astigmatism against the rule, .50 D. had 
to be deducted, just as in the left eye, where the astigmatism 
was with the rule. It must be remembered here, as I have 
already pointed out in Chapter II, that, when the chief merid- 
ians of curvature are at 45° and 135°, the exact halfway points 
between 0° and 90° on one side, and 90° and 180° on the other 
side of the 90°, the terms "with the rule" and "against the 
rule " do not strictly hold, for the meridians at these points 
are just as near to 90° as they are to 180°. In other words, 
they are on the dividing lines between astigmatism with the 
rule and astigmatism against the rule. Consequently the 
usual addition of .50 D. to the reading of the instrument, as 
in astigmatism against the rule, and the subtraction of .50 D. 
from it, as in astigmatism with the rule, does not hold very 
strictly in these cases. Knowing the axis of the astigmatism, 
however, the amount of it, even were it not indicated by the 
instrument, is usually easily obtained by the subjective test 
with the trial glasses, especially if the method of beginning 
the test with the weakest plus glass and gradually increasing 
it in strength is followed. For instance, in this case I began 
the subjective test, right eye, with+.25D. cylindrical glass, 
axis 135°, which was accepted with improvement in vision. 
Then +.50 D. cyl., same axis, was tried, but not accepted. 
Then +.25 D. sphere was added to the +.25 D. cyl., which 
improved vision. The spherical glass was increased in 
strength +.25 D. at a time, till the patient accepted +1.25 D.s 



96 THE REFRACTIO:^ OF THE EYE 

in addition to the +.25 D. cyl., axis 135°, which gave him the 
best vision. Exactly the same course was pursued with the 
left eye. 

I give a second case with axes like the above, but where 
both the astigmatism and spherical error are much greater 
in amount and associated with amblyopia. 

Case XXXIV. Large amount of compound 'hypermetro'pic 
astigmatisyn with the main meridians at 45° and 135°; Severe 
asthenopia-, Amblyopia; Relief with glasses. — July 15, 1898, 
M. B., aged thirty, in good general health, consulted me about 
her eyes because of great pain in them, and on account of 
vision blurring when she tried to do any close work. She 
has always had weak eyes, and has suffered greatly with 
them, but says she has been afraid to consult an oculist for 
fear that her sight would be made worse. 




R. E, 



L. E. 



Fig. 49. 



Ophthalmometer. — Astigmatism with the rule, 3D., axis 
45® -h or 135° — right eye ; astigmatism against the rule, 3D., 
axis 135* + or 45° - left eye. 



ILLUSTRATIVE CASES 97 

It will be noticed in this case that the instrument reads 
astigmatism with the rule in the right eye, and astigmatism 
against the rule in the left eye, while it was just the reverse 
in the preceding case. 

This is due to the fact that in each case we started at 
135° for the primary position (see rule for procedure in such 
cases, p. 17). A glance at Figs. 48 and 49 will show why 
the instrument thus records these cases. In Case XXXIII, 
right eye, the primary position was at the shortest curved 
meridian, 135°, consequently when the meridian at 45° was 
reached, the longest curved meridian, the mires separated, 
saying " astigmatism against the rule " ; while in the left eye 
the longest curved meridian was at 135°, the primary posi- 
tion, and when the mires were turned to the secondary position, 
45°, the shortest curved meridian, they overlapped, saying 
*' astigmatism with the rule." Now in Case XXXIV, right 
eye, the longest curved meridian was at 135°, consequently 
when the mires were turned to 45°, the shortest curved 
meridian, they overlapped, saying '* astigmatism with the 
rule" ; while in the left eye the shortest curved meridian 
was at 135°, and the longest curved meridian at 45°, there- 
fore the instrument read astigmatism against the rule, begin- 
ning with 135° as the primary position. 

Test cards and trial lenses. — 

R. V.= 2Vo -I^W. + 2.50D. 4- 2.75 D. cyl., 45°. 
L. V. = 2'A : 1^ W. + 2 D. + 2.75 D. cyl., 135°. 

Reads Jaeger No. 1 from 7 to 12 inches. 

Ophthalmoscope. — H. 8 D. at 135° and 5 D. at 45° right 
eye; H. 8D. at 45° and 5 D. at 135° left eye, 

A second test resulted in the patient accepting exactly 
the same glasses as at the first, and they were accordingly 
ordered. She has worn these glasses but a few weeks, but 
as they have relieved her headaches, and enabled her to do 



98 



THE REFRACTIOX OF THE EYE 



continuous fine needlework, it is fair to presume they will be 
of permanent benefit. 

Case XXXV. Astigmatism against the rule in one eye and 

with the rule in the other; Marked asthenopia; Relief ivith glasses. 
— April 24, 1895, Mr. C. C, aged forty-seven years, in mod- 
erately good health, has been unable to get a suitable glass, 
and that is why he consulted me to-day. The patient re- 
ceived a blow on his right eye mth a rubber ball when he 
was a child, and has never seen very well with that eye since. 

Ophthalmometer. — Astigmatism against the rule, .50 D., axis 
155° -h or Qo° — right eye ; astigmatism with the rule, .75 D., 
axis 105° -f or 15° — left eye. 

Test cards and trial lenses. — 

I^- ^'• = f* = l*^^-+l ^.+1 D. cyl., 155°. 
L. Y. = II : fl W. + .50 D. + .25 D. cyl., 105°. 

Reads Jaeger Xo. 1 at 8 inches with + 1.50 Ds. added to 
correct the presbyopia. 




R. E 



L. E. 



Fig. 50. 



ILLUSTRATIVE CASES 99 

Ophthalmoscope, —K. 2D. at 65° and ID. at 155° right 
eye ; H. 1 D. left eye, the astigmatism being too small to 
estimate with the ophthalmoscope. 

The patient accepted the same glasses on a second test that 
he accepted at first, and both reading and distance glasses were 
ordered. These glasses have been entirely comfortable, though 
he has used his eyes continuously in the capacity of a teacher. 
He was wearing when he came under my care a cylindrical 
glass at the wrong axis in the right eye, and in the left eye a 
cylindrical glass four times too strong, which were very good 
reasons for not having comfortable eyes and good vision. 

Case XXXVI. Ophthalmometer shows no corneal astigma- 
tism ; Patient accepts -\- .25 D. cylindrical glass against the rule 
in addition to a spherical glass. — November 29, 1895, Matilda 
P., aged ten years, in good general health, has for the last year 
suffered from headaches, burning, and soreness in the eyes 
after studying for a short time, especially in the afternoon and 
evening. 

Ophthalmometer. — Showed no corneal astigmatism what- 
ever. The lines dividing the mires into halves were straight 
with each other in all positions, and there was no overlapping 
or separation of the images after they were once approximated. 

Test cards and trial lenses. — 

R. V. = |0- : 1^ W. + 1 D. + .25 D. cyl., 180°. 
L. V. = 1^ : 1^ W. + 1 D. + .25 D. cyL, 180°. 

Reads Jaeger No. 1 from 4 to 12 inches. 

Ophthalmoscope. — H. 2D. in each eye. The astigmatism 
was too small in amount to be estimated with the ophthalmo- 
scope. 

A mild astringent wash was ordered for a conjunctivitis 
that was present, and the patient directed to return in a week 
for a second test. This test resulted in the patient accepting 



100 THE REFRACTION OF THE EYE 

the same glasses exactly as at the first, and they were ordered. 
The patient has been relieved of her headaches and eye symp- 
toms. About eighteen months after the glasses were ordered 
the patient returned, complaining that her eyes felt tired. 
With a tonic she was relieved of all eye trouble and without 
the change of glasses, and she continues her studies with com- 
fort to date, October, 1898. 

Case XXXVII. The ophthalmometer shows no corneal 
astigmatism; Patient accepts -}- -50 D. cylindrical glass against 
the rule. — July 19, 1895, Miss J. H. M., aged fifty years, in 
good general health, consults me on account of pain in the 
eyes and blurring of the vision on doing close work. She has 
worn glasses for seven years, but they have not been satisfac- 
tory. 

Ophthalmometer. — No corneal astigmatism. 

Test cards and trial 



E. V. =|^:ffW.H-.25D. + .50D. cyl.,180<'. 
L. V. = f^: f|W. + .50 D. + .50 D. cyl., 180°. 

Reads Jaeger No. 1 at 8 inches, with a + 2 D.s added to 
correct her presbyopia. 

Ophthalmoscope. — H. 1 D. at 90° and .50 D. at 180° in each 
eye. 

After one test I prescribed the glasses both for distance 
and for reading. Both have been worn for three years with 
entire relief from asthenopia. 

It will be noticed that the ophthalmometer read negative in 
the last two cases, or at least it showed no corneal astigmatism; 
and that in the first case, XXXVI, but +.25 D. cyl. against 
the rule was accepted ; while in the second case, XXXVII, 
-I-.50 D. cyl. against the rule was accepted, the customary 
amount in cases where there is no corneal astigmatism present. 
The difference in the strength of the cylindrical glasses 



THE INFLUENCE OF AGE ON ASTIGMATISM 



101 




accepted by these two patients may be accounted for in part, 
perhaps, by the fact that in Case XXXVI the patient is a 
child, in which case the lens is more elastic, the ciliary muscle 
stronger and possessed of 
more tonicity than in the 
older patient, and the mus- 
cle acting in an irregular 
way, as it is known to do 
sometimes, part of the len- 
ticular astigmatism may 
be corrected. In Case i^o 
XXXVII, however, the 
patient is presbyopic, the 
lens less elastic, the cili- 
ary muscle weakened, and, 
therefore, not so likely to 
correct any of the astigma- pj^. 5^^ 

tism by its irregular action. 

I am not unmindful of the fact that lenticular astigmatism 
is usually ascribed to a tilting position of the lens. But, grant- 
ing this, still the ciliary muscle might, by its irregular action, 
correct part of the astigmatism. 

I beg to be distinctly understood, however, that I do not 
advance this idea — the influence of age on the accommodation 
— to account for the discrepancies, sometimes present, in the 
readings of the ophthalmometer and the glasses accepted by 
the patient. I believe it accounts at times for a very small 
part of the discrepancy. To the more or less tilting of the 
lens must be ascribed the chief differences in amount in the 
lenticular astigmatism present. Usually it amounts to just 
.50 D., but it may be more or less, and at times is absent alto- 
gether. Hence the variations that we come across in practice, 
and which should not disturb us if only a little judgment and 
common sense are used in accounting for and correcting same. 



102 



THE REFRACTION OF THE EYE 



Case XXXVIII. Astigmatism with the rule, .25 D. ; Patient 
accepts + 50 D. cylindrical glass against the rule with relief from 
marked asthenopia. — September 18, 1896, Joseph R., aged forty- 
two years, in good health, has worn glasses for six years. He 
suffers from headaches, has dazzling sensations before the eyes, 
and blurring of vision after using his eyes for a short time. 

Ophthalmometer. — Astigmatism with the rule, .25 D., axis 
105° + or 15° — right eye ; astigmatism with the rule, .25 D., 




R. E. 



L. E. 



Fig. 52. 



axis 90° + or 180° - left eye. 
Test cards and trial lenses. — 



R. V. = 1^ : 1^ W. + .50 D. + .50 D. cyl., 15°. 
L. V. = f^ : If W. + .50 D. + .50 D. cyl., 180°. 

Reads Jaeger No. 1 at 8 inches with -h .50 D.s added to 
correct his presbyopia. 

Ophthalmoscope. — H. 1 D. at 105° and H. .50 D. at 15° right 
eye; H. 1 D. at 90° and H. .50 D. at 180° left eye. 



ILLUSTRATIVE CASES 103 

The second test resulted in the patient accepting exactly 
the same glass as on the first test. Both distance and reading 
glasses were ordered, and the patient has used his eyes with 
more comfort than ever before. In fact, has scarcely any 
trouble, though he uses his eyes steadily. 

In this case, while the ophthalmometer read astigmatism 
with the rule, .25 D., the patient accepted .50 D. cylindrical 
glass against the rule. This is to be accounted for, I think, by 
the presence of .75 D. of lenticular astigmatism. The corneal 
astigmatism of .25 D. neutralized that amount of the lenticular 
astigmatism, leaving .50 D. of it to be corrected by the glass 
which the patient accepted. 

Case XXXIX. Ophthalmometer shows corneal astigmatism 
with the rule^ .25 D. ; Patient accepts this amount exactly^ indi- 
cating no lenticular astigmatism whatever, — May 9, 1895, J. E. H., 
aged twenty-one years, in good health, has worn glasses for the 
last four years, but suffers continually with pains in the eyes, 
headaches, and nervousness. He is a bookkeeper, and the strain 
on his eyes is great. 

Ophthalmometer. — Astigmatism with the rule, .25 D., axis 
105° + or 15°- right eye; .25 D., axis 75° + or 165°- left 
eye. 

Test cards and trial lenses. — 

^' ^' = 11 • ff W- + ^^ ^' + -2^ ^' cyl., 105°. 
L. V. = 1^ : ff W. + 50 D. + .25 D. cyl., 75°. 

Reads Jaeger No. 1 at 5 inches. 

Ophthalmoscope. — H. ID. in each eye. 

On a second test, the same glass was accepted, and was 
ordered. With this glass he could follow his calling as a book- 
keeper, with comfort. As the patient is a friend, I see him 
frequently, and he tells me he has none of his old symptoms. 
He has worn the glasses for two and one-half years. 



104 



THE REFRACTIOX OF THE EYE 



Case XL. Astigmatism with the rule, .25 D.; Patient accepts 
,50 D. cylindrical glass against the rule, in combination with 
2 D.s ; Latent hypermetropia of 2 D. left uncorrected ; Marked 
asthenopia; Relief with glasses. — As regards the astigmatism, 
this case is similar to Case XXXVIII; that is, the corneal 
astigmatism of .25 D. is more than neutralized by the lenticu- 
lar astigmatism, leaving .50 D. of lenticular astigmatism to be 
corrected by a cylindrical glass. 




R. E. 



Fig. 53. 



L. E. 



May 29, 1894, William E., aged twenty years, in good health, 
family history good, has been troubled with his eyes since a 
child. Has headaches, and pains in the eyes after close work 
of any kind. He fitted himself to glasses five years ago, 
H- 1 D.s, but they have not been satisfactory. 

Ophthalmometer, — Astigmatism with the rule, .25 D., axis 
105° + or 15° - right eye ; 25 D., axis 75° + or 165° - left 
eye. 



ILLUSTRATIYE CASES 105 

Test cards and trial lenses. — 

R. V. = 1^ : ff W. + 1.50 D. + .50 D. cyl., 15°. 
L. V. = If : ff W. + 1.50 D. + .25 D. cyl., 165°. 

Reads Jaeger No. 1 at 7 inches. 

Ophthalmoscope, —YL. 4.50 D. at 105° and 4 D. at 15° right 
eye ; H. 4.50 D. at 75° and 4 D. at 165° left eye. 

On account of the large amount of latent hypermetropia 
present in this case, I gave him three tests, each time correct- 
ing the astigmatism in each eye separately ; then I placed equal- 
strength spherical glasses in front of each eye at the same 
time, beginning with + .25 D., and gradually increased their 
strength up to 2 D., which were as strong as the patient would 
accept. This spherical glass, in conjunction with the cylin- 
drical ones gave him ^^ vision, and they were ordered. Al- 
though 2 D. of latent hypermetropia remain uncorrected, these 
glasses have been worn for two and one-half years with entire 
relief from his asthenopic symptoms. In passing, it might be 
remarked that there was no insufficiency of any of the ocular 
muscles, and no tendency to squint. 

Case XLI. Astigmatism with the rule., 1.50 D. in the 
right eye., and 2 D. in the left., with 2 D. hypermetropia ; Fitted 
ivith glasses several times under a mydriatic^ with hut little benefit ; 
Complete relief with glasses fitted hy the aid of the ophtlialmome- 
ter without any mydriatic. — I report this case in connection 
with the one preceding, to show that it is unnecessary to make 
use of mydriatics in the great majority of cases of compound 
hypermetropic astigmatism, and that a mj'driatic may be of 
harm, as it proved in this case. 

June 4, 1896, J. A. R., aged thirty years, is in fairl}' good 
health, bat has very poor digestion and is not strong.i Has 
had one sister and one brother who died of consumption. The 

1 At this writing, October, 1808, I learn the doctor has developed con- 
sumption. 



106 THE refractio:n of the eye 

patient is a practicing physician in the West. For the last 
seven years his eyes have been a source of great annoyance to 
him. In fact, he has not been able to read or write for more 
than a few minutes at a time until a severe neuralgic pain 
would come in the eyes and forehead, so intense that he would 
have to stop his work. He says this pain was so great at 
times that it felt as if his eyes were being drawn out of his 
head. His eyes have been tested by competent men at least one- 
half dozen times under the influence of a mydriatic, but none 
of the glasses prescribed gave him anything more than partial 
relief, and then only for a short time. He has suffered greatly 
from photophobia, and of two oculists of this city whom he 
consulted besides myself, one was of the opinion that his chief 
trouble was " hypersesthesia of the retina," and advised no 
change of glasses from those he was already wearing. The 
other oculist whom he consulted, tested his eyes without the 
use of a mydriatic. His test and my own, made indepen- 
dently, agreed exactly in one eye, and differed but .25 D. in 
strength in the spherical glass in the other eye. No muscle 
insufficiencies were present. 

Ophthalmometer. — Astigmatism with the rule, 1.50 D., 
axis 90° + or 180° - right eye ; 2 D., axis 90° + or 180° - 
left eye. 

Test cards and trial lenses. — 

R. V. = 1^ : ff W. + .50 D. + 1.25 D. cyl., 90°. 
L. V. = ^Yo • f* W. + .50 D. + 1.75 D. cyL, 90°. 

Reads Jaeger No. 1 at 6 inches. 

Ophthalmoscope. — Yi. 1.50 D. at 90° and 2.50 D. at 180° 
right eye ; H. 1.50 D. at 90° and 3 D. at 180° left eye. Be- 
sides a slight hypereemia of the retina, the fundus was normal 
in each eye. 

Second test: the ophthalmometer read the same as on the 
first test. 



ILLUSTRATIVE CASES 

Test cards and trial lenses. — 



107 



R. V. 



20 
30 



20 
TO 



- W. + 1 D. + 1.25 D. cyl., 90°. 



L. V. = ^-^\ : f^ - W. + 1.25 D. -H 1.75 D. cyl., 90°. 
Reads Jaeger No. 1 at 6 inches. 



1:80 




Fig. oi. 

Ophthalmoscope. — Shows the same as at the first test. 

A third test resulted in the patient accepting exactly the 
same glasses as on the second test, and they were ordered. 
These glasses gave him entire relief from his asthenopic symp- 
toms, and he was able to use his eyes with comfort for long 
hours for the first time in seven years. It is now more than 
two years since he was ordered these glasses, and they are still 
satisfactory. 

He was wearing when he came to see me + 1.75 D. + .75 D. 
cyl., 90° right eye, and + 1.75 D. + 1.25 D. cyl., 90° left eye. 
Atropine in the hands of a half dozen competent men had 
been a failure in his case, simply because they overfitted the 
spherical error and underfitted the astigmatic error. 

Roosa, long ago, pointed out the fact that in young sub- 



108 THE REFRACTION OF THE EYE 

jects we may often leave one, two, and in some cases even as 
much as three, diopters of latent hypermetropia uncorrected 
without harm. Especially, I think, in those cases where the 
astigmatism is large in amount and the latent hypermetropia 
small or only moderately large in amount, it is safe to let the 
latent hypermetropia go uncorrected. The younger the subject, 
the more latent hypermetropia may be left without harm. The 
following is a good example of this class of cases. 

Case XLII. Astigmatism of large amount, with moderately 
large amount of latent hypermetropia^ which latter was left uncor- 
rected; Complete relief of the asthenopia hy correction of the astig- 
matism. — October 6, 1893, Alma S., aged twenty-four years, 
in good health, has had trouble with her eyes since childhood, 
but has never had them examined. Her eyes pain and her 
head aches after she uses the eyes for any close work ; in fact, 
she cannot use the eyes for more than a short time without 
resting them, particularly in the evening. 

Ophthalmometer. — Astigmatism with the rule, 5 D., axis 
60° + or 150° - right eye ; 5 D., axis 105° + or 15° - left eye. 

Test cards and trial lenses. — 

^- ^- = f F • f^ ^^'- + 4.25 D. cyl., 60°. 
L. V. = f^ : 1^ W. + 4.25 D. cyl., 105°. 

Reads Jaeger No. 1 at 6 inches. 

Ophthalmoscope. — Yi. 2.50 D. at 60° and 6.50 D at 150° 
right eye ; H. 1.50 D. at 105° and 6 D. at 15° left eye. 

On a second test the patient accepted exactly the same 
glasses as at the first test, and they were ordered. They have 
been worn constantly since, with relief of the asthenopic symp- 
toms from which she suffered. In this case a latent hyper- 
metropia of about 2 D. was left uncorrected in each eye. 

While these last few cases have been given to emphasize 
the fact that it is not necessary to use a mydriatic in the great 
majority of cases, even where there is considerable amount of 



SPASM OF ACCOMMODATIOI!^ 



109 



latent hypermetropia present, yet there are exceptional cir- 
cumstances under which a mydriatic is necessary in order to 
fit glasses. I refer to spasm of accommodation. 



150 




R. E. 



L. E. 



Fig. 55. 



Spasm of Accommodation 

Spasm of accommodation may be present in any form of 
error of refraction, but it is met with more frequently in 
hypermetropia, hypermetropic astigmatism, and mixed astig- 
matism, than in myopic cases. Fortunately, spasm of accom- 
modation is a comparatively rare condition, and the cases 
where it is necessary to use a mydriatic to suspend the 
accommodation are very few.^ 

In support of this statement the reader is referred to 
papers by Roosa,^ George J. Bull,^ of Paris, myself,"* and to 

1 Of course strabismus cases are here excluded. They will be discussed in 
a separate chapter. 

2 Trans. Med. Soc, state of New York, February, 1891. 
^ Ophthalmic Beview, London, September, 1895. 

* New York Medical Journal, September 10 and October 8. 1892, and June 
20, 1896. 



110 THE REFRACTION OF THE EYE 

the writings of American and European oculists in the last 
few years. 

Let me, also, emphasize the fact that it is not necessary to 
use a mydriatic in every case of spasm of accommodation ; for, 
in many cases of spasm of accommodation, if the cause for it is 
found out and removed, the spasm disappears. Two questions 
of importance are to be considered in discussing spasm of 
accommodation : first, how to recognize it ; second, how to 
treat it, especially in regard to fitting glasses. 

Hotv to recogni?:e spasm of accommodation. — The most im- 
portant of the subjective symptoms are : (1) Sudden variability 
in vision in reading the' test cards for distant vision. For 
example, testing one eye at a time, the patient reads all of the 
letters on the Snellen card down to and including the J-§- line, 
when suddenly the letters fade out, and the patient is not able 
to read more than y2_o_ perhaps. Allow the patient to rest a 
moment with the eyes closed, then repeat the test, and the 
same thing will likely happen again. This condition may be 
present in only one eye, but usually it is present in both, if 
present at all. This sudden failure of the vision is evidently 
due to sudden contraction or spasm of the ciliary muscle, 
which allows the crystalline lens to expand, and the eye to 
become temporarily myopic (false or spasmodic myopia). 
This condition, of course, makes the distant vision bad. 
(2) Changeableness in appearance of the lines on the clock-dial. 
For instance, say we have a case of simple hjqDcrmetropic astig- 
matism with the rule, and a tendency to spasm of accommoda- 
tion. This patient when he first looks at the clock-dial may 
see the horizontal lines plainest (as he should if no spasm of 
accommodation was present), but in a moment the vertical 
lines appear plainest and the horizontal lines become dim. 
Evidently in such case the spasm of the ciliary muscle has con- 
verted the simple hypermetropic astigmatism into a myopic 
astigmatism with the rule, for in myopic astigmatism with the 



SPASM OF ACCOMMODATION^ HI 

rule the vertical lines are seen plainest. (3) A sense of con- 
traction of drawing in the eyeball is felt. (4) Variability in 
the glasses accepted by the patient during the test, e.g., a 
patient accepts a plus glass one minute and in the next refuses 
it, or, perhaps, accepts a minus glass, quickly changing from 
one to the other ; or, he may accept a strong plus glass one 
minute and only a weak one the next. 

The objective symptoms are : (1) Where the ophthalmo- 
scopic examination shows the refractive condition of the eye 
to be widely different from the glasses accepted on subjective 
examinations. For instance, the patient has accepted + 1 D. 
spherical glasses when the ophthalmoscope shows him to be 
hypermetropic by 5 D. Or, say the patient has accepted 
— ID. spherical glasses when the ophthalmoscope shows him 
to be actually hypermetropic. Not infrequently the patient 
will relax his spasm of accommodation under an ophthalmo- 
scopic examination when he will not under a subjective exam- 
ination. This I think due chiefly to the fact that under an 
ophthalmoscopic examination the patient is in a dark room, 
with pupils dilated, and looking in the distance at nothing in 
particular, having nothing, therefore, to stimulate his accom- 
modation ; while, under a subjective examination, the patient 
is looking intently at letters, trying to figure them out, and 
this of itself many times incites the ciliary muscle to action. 
(2) Where the retinoscope shows sudden changes in the 
refractive condition of the eye, perhaps indicating hyperme- 
tropia one instant and myopia the next, and where the glasses 
accepted by the retinoscopic test do not give uniform good 
vision. (3) In cases of astigmatism where the glasses 
accepted vary widely from, the reading of the ophthalmometer, 
it is often an indication of spasm of accommodation. 

The above are the chief symptoms of spasm of accommo- 
dation, and, as a rule, the condition is easily recognized by 
them, many times by means of only one or two of them. 



112 THE REFRACTION OF THE EYE 

Of the subjective symptoms, the sudden change in the acute- 
ness of vision is the most constant and reliable one ; and of 
the objective symptoms, that discovered by the ophthalmo- 
scope is the most reliable one. 

Mow to overcome sjjasm of accommodation. — When once satis- 
fied that there is a spasm of accommodation, or a tendency 
to it, I look for the cause, and try to remove that, before I 
hastily resort to the use of some mydriatic. For, even though 
we do use a mydriatic and fit the patient, the patient is often 
unable to wear the glasses unless the cause of spasm is gotten 
rid of. Unless, indeed, as has been recommended and prac- 
ticed by some oculists in this country, atropine is continued 
for weeks after the glasses have been fitted, which, in my 
opinion, is altogether bad practice. The much better plan is 
to seek for and remove the cause. Failing in that, then 
mydriatics are called for, but not until then. In exceptional 
cases, no apparent cause can be discovered to account for 
spasm of accommodation. 

Some of the most prominent causes of spasm of accom- 
modation are : (1) conjunctivitis ; (2) insufficiency of the 
internal recti muscles ; (3) contusion ; (4) sympathetic irrita- 
tion, though many times contusion and sympathetic irritation 
are accompanied with paresis of accommodation ; (5) gener- 
alized spasmodic affections ; (6) overwork of the eyes ; 
(7) hypersesthesia of the retina ; (8) beginning the test for 
glasses with minus glasses ; (9) idiopathic cases. 

These are the chief causes of spasm of accommodation. 
Many times, where the test for glasses at first has been- 
unsatisfactory, and a tendency to spasm, or actual spasm, of 
accommodation was present, I have succeeded in fitting glasses 
by first treating the lids for a week or ten days with a 
mild astringent wash. A conjunctivitis of a mild type will 
often cause enough irritation of the ciliary muscle to render 
a test for glasses unsatisfactory. Again, where the patient 



ILLUSTRATIVE CASES 113 

has been using the eyes excessively for a day or two 
before coming for a test, it is often necessary to make him 
rest the eyes or use them easily for a day or two, before 
giving the final test. In hypersesthesia of the retina, shaded 
glasses worn for a few days before the test is desirable. If 
insufficiency of the internal recti muscles is present, a week 
or two of treatment with strych. sulphate, in increasing 
doses, with outdoor exercise and rest, will usually suffice to 
relieve it, and leave the eyes in condition for testing. ^ 

So with the other causes of spasm of accommodation 
when present, I try to remove them. If no apparent cause 
is to be found, and if the second test for the glasses is not 
satisfactory, and does not substantially agree with the first, 
I do not hesitate to use a mydriatic, and a strong one. Sco- 
polamine and atropine are the two I employ. The method 
of their use I have already pointed out in the first part of 
this chapter. 

I now give some cases illustrative of the condition of 
spasm of accommodation. 

Case XLIII. Compound hypermetropic astigmatism toith 
the rule; Spasm of accommodation; Amblyopia ; Atropine used, 
and but little difference found between the glasses fitted without 
atropine and those fitted under it. — June 25, 1891, Gussie L., 
aged fifteen, is in poor general health. Her eyes have troubled 
her since six years of age, when she entered school. She was 
never able to see the blackboard well, was nervous, and found 
it hard to sit still for any great length of time. At present 
she has headaches, and pains in the eyes on using them for 
close work. 

Ophthalmometer. — Astigmatism with the rule, 1.50 D., axis 
90° + or 180° - in each eye. 

1 For the methods of testing the strength of the external ocular muscles, see 
the chapter on Strabismus. 



114 THE REFRACTIOX OF THE EYE 

Test cards and trial lenses. — The lines on the clock-dial 
were entirely unsatisfactory as a test. 

R- V. = jVo ■■ iVo W. - 2 D - 1 D. cyL, 180'. 
L- V. = jVV = tVo W. - 2 D - 1 D. cyL, 180°. 

During the test there were signs of spasm of accommoda- 
tion, for first one set of lines on the clock-dial would appear 
plainest, then another set; and the vision at one moment 
would be fairly good and the next moment very poor. I 
therefore began to test both eyes at once, even for the astig- 
matism, and as the ophthalmometer showed it to be exactly 
the same in each eye, it was easy to do so. Placing -|- .25 D. 
cyl., 90°, before each eye, the vision was somewhat improved, 
and I gradually increased the strength up to -f ID. cyl., the 
vision improving para passu. With a stronger -f cyl. the vision 
was not so good as with the -f- 1 D. cyl., so I stopped at that 
point. With the cylindrical glasses in position, weak plus 
spherical glasses were tried before both eyes at once with 
improvement in vision, and they were gradually increased up 
to + 1 D. sphere. Testing in this way both eyes at the same 
time, the patient accepted H- 1 D. + 1 D. cyl., 90°, and the 
vision was brought up to f^ in each eye. 

Ophthalmoscope. —YL. 2D. at 90° and 3.50 D. at 180° in 
each eye. 

Atropia sulphate, solution of four grains to one ounce, was 
ordered instilled, one drop in each eye three times a day for 
four days, and then a second test was made. 

The ophthalmometer read exactly the same as at the first 
test. 

Test cards and trial lenses. — 

R. V. = 2^^ • 1^ W. -h 2 D. + 1.25 D. cyl., 90°. 
L. V. = 2V0 • I* W. 4- 1.50 D. + 1.25 D. cyl., 90°. 



ILLUSTRATIVE CASES 



115 



Ophthalmoscope. — H. 2 D. at 90° and 3.50 D. at 180° right 
«ye ; H. 1 D. at 90° and 2.50 D. at 180° left eye. Retinoscopy 
confirmed the other tests. 

One week after the test under atropine, the patient was 
subjected to a third test. She accepted + 1.25 D, -|- 1.25 D. 
cyL at 90° right eye, and 
+ 1 D. + 1.25 D. cyL 
at 90° left eye, and these 
glasses were ordered. It 
will be noticed that they 
differ but slightly from 
the ones that the patient 
accepted before atropine 
was used, that is, when 
both eyes were tested at 
once. In fact, they differ 
so little that I believe she 
would have been almost, 
if not quite, as comfort- 
able with the former as 
she is now with the latter, which give her entire relief from 
her asthenopia. Her poor vision, however, which later I found 
to be due simply to amblyopia, and the fact of her accepting 
minus glasses at first when the eyes were tested separately, 
induced me to use a mydriatic. Under tonics and outdoor 
exercise her general health improved. 

Case XLIV. Compound hypermetropic astigmatism against 
the rule; Spasm of accommodation ; Mild conjunctivitis; Hyper- 
cesthesia of the retince; Scopolamine used, — November 20, 
1895, Miss C. A. F., aged twenty-two years, in good general 
health, consulted me first for a catarrhal conjunctivitis. She 
states that about two years ago she had a very severe inflam- 
mation in the eyes following measles, and was confined to a 
darkened room for five months on account of the light which 




Fig. 56. 



116 THE REFRACTIOX OF THE EYE 

hurt her eyes. She had glasses fitted shortly afterward, but 
her eyes have continued to j^ain her. 

Ophthalmometer. — Shows no corneal astigmatism. 

Test cards and trial lenses. — 

^' ^^' = M - • M ^^- + -25 D. cyl., 180°. 
L.V.=|| :|^W. + .25D.cyl., 180°. 

Reads Jaeger Xo. 1 at 4 inches. 

Ophthalmoscope. — H. ID. in each eye ; no astigmatism 
could be estimated with the ophthalmoscope. 

Although both eyes were tested at the same time, the patient 
would not accept any stronger glasses. Xeither was retino- 
scopy of benefit in fitting the case. During the test the patient 
would be able to read |^ at one moment, then the vision would 
blur and she could not read more than |-^. She also complained 
of drawing sensations in the eyes. 

Scopolamine, -J per cent solution, was instilled, one drop in 
each eye every five minutes for six successive times, and then 
after a wait of half an hour a second test was made. 

Second test, under scopolamine. 

OpfhtJialmometer . — Xo corneal astigmatism. 

Test cards and trial lenses. — 

^' ^'- =H •' I* ^^'- + 1 D. + .25 D. cyl., 15°. 
L- V. = f^ : 1^ W. + 1 D. + .25 D. cyl., 165°. 

Ophthalmoscope. — Showed the same amount of H. as at the 
first test. 

Three days later, when the patient was out from under the 
influence of the mydriatic, a third test was made, with the 
following result : — 

R. y. = 1^- : 14 W. + .25 D. + .25 D. cyl., 15°. 

L. v. = 1^ : 1^ W. + .25 D. + .25 D. cyl., 165°. 



ILLUSTRATIVE CASES 117 

This last glass was prescribed, and the patient had almost 
immediate relief from her asthenopia, although it required 
weeks to relieve the photophobia. In fact, a bright light, as 
the glare of tlie sun on the water, still troubles her considerably. 

Case XLV. Hypermetropia of large amount; Spasm of 
accommodation ; Asthenopia; Atropine used ; Relief with 3 D. 
of latent hypermetropia left uncorrected. — June 16, 1896, Bella 
K., aged fourteen, in good health, complains of her eyes hurting 
her when she tries to do close work, and of a drawing sensation 
in the eyes at times. She has always had " weak eyes " and 
often suffers from headaches. 

Ophthalmometer. — Astigmatism with the rule, .25 D., axis 
105° + or 15°- right eye ; .25 D., axis 75° + or 165°- left eye. 

Test cards and trial lenses. — 

R. V. = f^ - : ff W. + .50 D. + .25 D. cyl., 105°. 

L. y. = f^ - : f^ W. + 1 D. + .25 D. cyl., 75°. 

Reads Jaeger No. 1 from 4 to 16 inches. 

Ophthalmoscope. — H. 3D. in each eye. 

As the patient had signs of spasm of accommodation, first 
being able to read well then the vision blurring, sense of con- 
traction in the eyes, accepting a weak cylindrical glass and 
then refusing it, etc., I decided to use a mydriatic, especially as 
the ophthalmoscope showed at least three diopters of hj'per- 
metropia. Atropine, 4 gr. to 5Tsol., was ordered instilled, one 
drop three times a day for three days. 

Second test, under atropine. 

Ophthalmometer gave the same reading as at the first test. 

Test cards and trial lenses. — 

R V — -2JL • 2 _ w . 5 D 



118 THE REFRACTION OF THE EYE 

Ophthalmoscope. — H. 5 D. right eye; H. 6 D. left eye. 

Third test, one week later, the patient accepted + 2 D. 
right QjQ and + 2.50 D. left eye. These glasses were ordered, 
and though they left about three diopters of hypermetropia in 
• each eye uncorrected, yet they have been worn with comfort 
and relief from asthenopic symptoms for a period of two years. 
This patient would not relax the accommodation when both 
eyes were tested at once, and even after being under atropine 
and coming out she yet had 3 D. of latent hypermetropia. 
Nevertheless, since with + 2 D. right and + 2.50 D. left the 
vision was |-| — and steady, without signs of spasm of ac- 
commodation, I left the latent hypermetropia to take care of 
itself. 

I make this distinction between spasm of accommodation and 
latent Kypermetropia. In spasm of accommodation the vision is 
variable, that is, it changes from one moment to another, often 
with sensations of drawing in the eyes, and the ophthalmoscopic 
and retinoscopic examinations show the refraction to vary ; 
while in latent hypermetropia the ciliary muscle is able to and 
does correct steadily and without irregular action that portion 
of the total hypermetropia which is latent. As long as the 
ciliary muscle can do this with comfort and without strain, the 
latent hypermetropia remains practically the same, at least does 
not vary suddenly, and the subjective examinations do not 
discover it, unless when for some special reason we use a 
mydriatic. As the patient grows older, however, or becomes 
ill or overworked, the ciliary muscle may not be able to keep 
up its steady action, and begins to manifest signs of fatigue and 
to act irregularly, or with spasmodic action, if you please, with 
the result of variability in vision, a sensation of drawing in the 
eyes, headaches, etc. It is at this time that aid to the ciliary 
muscle is called for and should be given, but as long as an eye 
can work with comfort, and without bother to the patient, I 
believe it good policy to let it alone. 



ILLUSTRATIVE CASES 119 

I shall give here also a single case of spasm of accommoda- 
tion occurring in simple hypermetropic astigmatism ; but for 
cases of spasm of accommodation occurring in myopia, myopic 
astigmatism, and mixed astigmatism, I shall give them when 
treating those subjects. 

Case XL VI. Simple hypermetropic astigmatism; Spasm of 
accommodation; Marked asthenopia; Minus cylindrical glasses 
accepted without atropine and perfect vision obtained; Plus 
cylindrical glasses accepted under atropine and perfect vision. — 
April 5, 1892, Herminia T., aged nineteen years, in good health, 
has been troubled with her eyes for the last four years, in fact, 
more or less ever since she entered school. She cannot read 
or sew for any great length of time without getting pain in the 
eyes, and if she persists in her work her head aches. Some 
slight injection of the conjunctiva. 

Ophthalmometer. — Astigmatism with the rule, 1.25 D., axis 
90° 4- or 180° - each eye. 

Test cards and trial lenses. — The vertical lines on the clock- 
dial appeared plainest. 

R. V. = 1^ : If - W. - .75 D. cyl., 180°. 
L. V. = If : ff - W. - .75 D. cyl., 180°. 

Reads Jaeger No. 1 from 6 to 15 inches. 

Ophthalmoscope. — Emmetropia vertical meridian (90°) and 
H. .50 D. in horizontal meridian (180°) in each eye. 

Although both eyes were tried at once, the patient would 
accept nothing but minus glasses. Retinoscopy indicated 
myopic astigmatism. A wash was prescribed for the mild 
conjunctivitis, the patient ordered not to use the eyes so 
hard, and to report in a week. A second test was given, with 
exactly the same result as on the first test. Signs of spasm of 
accommodation were present. Atropine, solution 1 gr. to oi, 
was ordered instilled, one drop three times a day for three 
days. 



120 



THE REFRACTION OF THE EYE 



Test under atropine : ophthalmometer read the same as on 
the two previous tests. 

Test cards and trial lenses. — The horizontal lines on the 
clock-dial were seen plainest now. 

^' V- = 1^ • ft - w- + -^^ ^' cyi-. 90°. 
L. V- = If : ff - ^^' + '^^ ^' cyi-^ 90°. 

A week later, when the effect of atropine was out of the 
eye, the patient again accepted + .75 D. cylindrical glass, axis 




Fig. 57.- 



Showing how a simple minus cylindrical glass can convert a simple hyper- 
metropic astigmatism into simple hypermetropia. 



90,° in each eye, and it was ordered. These glasses have been 
worn for more than four years, and with relief from her asthe- 
nopic symptoms. 

In some cases of simple hypermetropic astigmatism a patient 
will accept a minus cylindrical glass and get relief from all 
asthenopic symptoms. This is to be explained, I think, by 
the fact that the patient, in accepting a simple myopic cylin- 
drical glass, converts the simple hypermetropic astigmatism 
into a simple hypermetropia (see Fig. 57). By so doing, the 



ILLUSTRATIVE CASES 121 

ciliary muscle can then act in its entire circumference and cor- 
rect the simple hypermetropia of small amount with ease and 
without fatigue ; whereas it could not correct an equal amount 
of simple hypermetropic astigmatism, because, in that instance, 
it would be compelled to contract irregularly, and in that way 
cause asthenopia or painful vision. 



CHAPTER V 

SIMPLE MYOPIC ASTIGMATISM — MYOPIA— SPASMODIC OE EALSE 
MYOPIA — RULE FOR PRESCRIBING NEAR OR READING 
GLASSES IN HIGH DEGREES OF MYOPIA — PRESBYOPIA AND 
THE TRANSPOSITION OF GLASSES FROM DISTANCE TO READ- 
ING IN MYOPES WHEN IT IS PRESENT 

The ophthalmometer, except in an indirect way already 
discussed in a previous chapter, does not reveal the nature of 
the error of refraction. This has to be found out with the 
trial case and test cards, the ophthalmoscope and retinoscope. 
So in myopia we make the same measurements with the oph- 
thalmometer as in all other cases. Furthermore, I begin the 
test with plus glasses just as I do in all cases, because, not 
knowing the nature of the error of refraction, it is safe to 
begin only with plus glasses. Should the patient prove to be 
hypermetropic, and minus glasses are tried first, they often 
incite a spasm of accommodation and are accepted when they 
should not be ; while, if plus glasses are begun with, we can 
be sure they will not be accepted by a myope, and we can find 
this out by the trial of only two or three glasses and without 
the risk of inciting spasm of accommodation. Of course, if 
the ophthalmoscope is used before glasses are tried, that 
indicates the kind of glass to be tried first. As a rule, how- 
ever, I prefer not to make an ophthalmoscopic examination 
until I have tried the test cards and trial case, because, if light 
is thrown into the eyes for any considerable time just before 
testing the vision, it often impairs the value of the test. 

Perhaps before giving illustrative cases it is well to make 
a clear distinction here between true or axial myopia and false 

122 



) 



THE DIFFERENT FORMS OF MYOPIA 



123 




Fig. 58. — True or axial myopia, par- 
allel rays focussing in front of the 
retina, crossing and forming dif- 
fusion circles on the retina. 



or spasmodic myopia. True myopia is where the axis of the 
eye is too long, allowing the rays of light to focus in front 
of the retina (see Fig. 58). This may be small or large in 
amount, according to the increase 
of length of the eyeball beyond 
the length of the emmetropic 
eye, which latter is about 23 mm. 
When the eye becomes elongated 
rapidly, attended with changes in 
the choroid and sclera, with poste- 
rior staphyloma, etc., we call this 
progressive or malignant myopia. 

False myopia is nothing more than a spasm of the ciliary or 
focussing muscle. To illustrate, say the patient is emmetropic, 
but from some cause the ciliary muscle is overacting. By so 
doing the eye is rendered myopic by the lens becoming thicker, 
and causing the rays to focus in front of the retina. Further- 
more, this patient would accept minus glasses with improve- 
ment in vision, as long as this spasm of accommodation lasted. 
False myopia may be present even in hypermetropia, the 
focus being changed from back of the retina to the front of 

it by the spasm of accommodation. 
Again, false myopia may be present 
in the same eye with true myopia, 
that is, the spasm of accommoda- 
tion increases the true myopia. 

It is altogether important to 
recognize the difference between 
true and false myopia ; for, while 
the true myopia should be care- 
fully corrected, false myopia should never have a gla^s pre- 
scribed for it, but its cause should be looked for and reme- 
died, if possible, upon wliich it disappears and requires no 
further treatment. 




Fig. 59. — False myopia in an em- 
metropic eye, due to spasm of 
accommodation. Dotted line 
shows false focus. 



124 



THE REFRACTIOX OF THE EYE 




Fig. 60. — Curvature myopia, 
where the length of the eye- 
ball is normal, but the cor- 
nea is too much curved. 



Of curvature myopia it is hardly worth while to speak, more 
than to say that such a thing exists. It is due to excessive 

curvature of the cornea, and not 
to lengthening of the eyeball (see 
Fig. 60). 

It is a rare error of refraction, 

and when present is usually due to 

some pathological condition, conical 

cornea, staphyloma of the cornea, 

etc., for which conditions glasses 

are of but little benefit. 

Of the rule of procedure in giving distance and reading 

glasses in high degrees of myopia, and of the transposition of 

glasses in presbyopia in myopic cases, I shall speak later in this 

chapter, giving appropriate illustrative cases. 

Case XLVII. Simple myopic astigmatism with the rule; 
Blepharitis marginalia; Slight asthe^iopia; Relief of blejjharitis 
with use of glasses and local treatment. — October 26, 1896, 
Charles Q., aged twenty-nine years, in good health, always had 
poor vision, and for the last four years his eyelids got red at 
the edges when he used his eyes for close work of any kind. 
There is but little pain in the eyes, but the lids itch and burn. 
He has no headaches. 

Ophthahnometer . — Astigmatism with the rule, 3 D., axis 
90° + or 180° - in each eye. 

Test cards and trial lenses. — 



^' ^- = M • ff ^^- - 2.50 D. cyl., 180°. 
L. V. = 1^ : ff W. - 2.50 D. cyl., 180°. 

Reads Jaeger No. 1 at 12 inches. 

Ophthalmoscope. — Myopia 3 D. at 90° and emmetropia at 
180° in each eye. 

A wash of boracic acid solution was ordered to cleanse the 



ILLUSTRATIVE CASES 



125 




lids with twice a day, and an ointment of yellow oxide of 
mercury, eight grains to one ounce of vaseline, to rub on the 
eyelids at night. 

Two weeks later the lids 
were very much improved in 
appearance. A second test for 
glasses was made, and the pa- 
tient accepted exactly the same 
glasses as at the first test. 
Ordered - 2.50 D. cyl., 180°, 
for each eye, which have been 
worn with an entire relief from 
the lid trouble. 

In this case, the test was 
begun with plus cylindrical 
glasses, just as I do in all 
cases where the ophthalmome- 
ter indicates astigmatism, but, 
as vision was made worse, minus cylindrical glasses were im- 
mediately tried and with improvement in vision. 

Their strength was gradually increased up to — 2.50 D., 
when vision was brought up to |^|. No minus spherical glasses 
were tried in addition to the cylindrical glasses in this case, 
for the ^^ vision, obtained by the patient with simple cylindri- 
cal glasses, was proof that no myopia was present in addition 
to the astigmatism. 

Case XLVIII. Simple myopic astigmatism with the rule ; 
Some amblyopia ; Relief with glasses. — March 23, 1895, J. H. B., 
aged eighteen years, in good health, complains of poor vision 
for distance, and of some difficulty in reading and writing. 
He has a tendency to half shut his eyes when he tries to see 
plainly. 

Ophthalmometer. — Astigmatism with the rule, 3.50 D., axis 
90° + or 180° - in each eye. 



Fig. 61. — Showing myopia of 3 D. in 
the vertical meridian, and emme- 
tropia in the horizontal meridian. 



126 THE REFRACTION OF THE EYE 

Test cards and trial lenses. — The vertical lines on the 
clock-dial are seen plainest in each eye. 

]R. V. = ^ : 1^ W. -3D. cyL, 180°. 
L. V. =f^:f^W. -3D. cyl., 180°. 

Ophthalmoscope. — Myopia 3 D. at 90° and emmetropia at 
180° in each eye. 

On a second test the patient accepted the same glasses as 
at first, and —3D. cyl., 180°, was ordered for each eye. 

In this case, as vision was not brought to |^ with simple 
minus cylindrical glasses, I suspected myopia to be present in 
addition to the astigmatism. I therefore tried minus spherical 
glasses in addition to the cylindrical glasses, but they did not 
improve vision any. The ophthalmoscope showed the fundus 
of each eye to be healthy, so the poor vision was attributed to 
amblyopia. The simple cylindrical glasses have been worn 
with comfort for more than three years. 

Case XLIX. Simple myopic astigmatism with the rule of 
large amount; Amblyopia^ and a mild form of asthenopia: — 
July 7, 1892, Frank H., aged eleven years, in good health, 
complains that he has always seen badly, but has not had much 
pain in his eyes. He holds his reading matter entirely too 
close to his eyes, and has to squeeze the lids almost together, 
in order to see even fairly well. He has never worn a glass. 

Ophthalmometer. — Astigmatism with the rule, 4.50 D., 
axis 105° + or 15° - right eye ; 4.50 D., axis 75° + or 165° 
— left eye. 

Test cards and trial 



R- V. = iVo = ltW.-4D. cyl.,15°. 
L. V. = ^-V : fi W. - 4 D. cyl., 165' 
Reads Jaeger No. 1 at 10 inches. 



ILLUSTRATIVE CASES 127 

Ophthalmoscope. — Myopia 5 D. at 105° and emmetropia 
at 15° right eye ; myopia 5 D. at 75° and emmetropia at 165° 
left eye. 

As the patient accepted only — 4 D. cylindrical glass, it 
shows that the estimation with the ophthalmoscope of 5 D. of> 
myopia in the shortest curved meridians was too high by 
1 D. The fundus of each eye was normal. There was a 
scleral ring at the temporal side of each disk. 

A second test, three days later, resulted in the patient 
accepting the same glasses as at the first test, and they were 
ordered. 

Here again, as in Case XL VI II. on account of the amblyo- 
pia, vision being brought up to only -|^ with simple cylindrical 
glasses, myopia in addition to the astigmatism was suspected. 
Minus spherical glasses, therefore, were tried in addition to 
the cylindrical glasses ; but they did not improve vision any. 
The somewhat poor vision, ^, was attributed to amblyopia, as 
the ophthalmoscope showed the fundi to be normal. 

Case L. No corneal astigmatism; Patient accepts — .50 D. 
cylindrical glasses against the rule; Relief from asthenopia. — 
April 24, 1894, James A., aged twenty-three years, in excellent 
health, has been troubled with his eyes for the last two years. 
After using the microscope or ophthalmoscope he has pains in 
the eyes, and if he persists in using his eyes, headaches follow. 

Ophthalmometer. — No corneal astigmatism wdiatever. 

Test cards and trial lenses. — The horizontal lines on the 
clock-dial were seen plainest. 

R. y. = |^_: i|W. -.50D. cyl., 90°. 

L. V. = I J - : ff W. - .50 D. cyl., 90°. 

Reads Jaeger No. 1 from 4 to 20 inches. 
Ophthalmoscope. — Myopia .50 D. at 180° and emmetropia 
at 90° in each eye. 



128 



THE REFRACTION OF THE EYE 



■180 




A second test resulted in the patient accepting exactly the 
same glasses as at the first test, and they were ordered, with 

consequent complete relief of his 
asthenopia. 

The retinoscope was used in 
this case to advantage, as it in- 
dicated myopia of a small amount 
in the horizontal meridian. The 
lines on the clock-dial were of 
service also, as they indicated 
either hypermetropic astigmatism 
with the rule, or a myopic astig- 
matism against the rule. Keep- 
ing in mind also the fact that, 
most of the time, when there is 
no corneal astigmatism, there is 
usually a small amount of lenticu- 
lar astigmatism against the rule, 
I began the test with a plus cylin- 
drical glass, with the axis at 180°. But it made vision worse, 
so I tried minus cylindrical glasses at 90°. They improved 
vision, the patient accepting — .50D. cyL, 90°, and getting 
the best vision. 

Case LI. Sim'ple myopie astigmatism with the rule in the 
right eye ; Lenticular astigmatism against the rule in the left eye^ 
the ophthalmometer showing no corneal astigmatism ; Asthenopia ; 
Relief with glasses. — November 29, 1895, M. L. H., aged 
twenty-five years, in good health, is a designer of wall papers, 
which occupation requires very acute vision. The patient com- 
plains that for the last two months her eyes have ached and 
pained her, and also that her head ached if she persisted in 
using her eyes for an hour or two at her work. 

Ophthalmometer. — Astigmatism with the rule, ID., axis 
90° -f- or 180°— right eye ; no corneal astigmatism left eye. 



Fig. 62. — Showing myopic astigma- 
tism against the rule — emme- 
tropia in the vertical meridian 
and myopia in the horizontal 
meridian. 



■■ 



■Mi 



ILLUSTRATIVE CASES 



129 



Test cards and trial lenses. — The lines on the clock-dial 
were unsatisfactory. 

^- ^- =!*= fo-W- - '^'^D. cyl., 180°. 
L. V. = 1^ : 1^ W. - 50 D. cyl., 90°. 

Reads Jaeger No. 1 from 6 to 12 inches. 

Ophthalmoscope. — Myopia ID. at 90° and emmetropia at 
180° right eye; myopia .75 D. at 180° and emmetropia at 90° 
left eye. 



180 




180 




R. E. 



Fig. 63. 



L. E. 



The retinoscope confirmed the ophthalmoscopic examination 
and the subjective test. 

A second test was made, and the patient accepting the same 
glasses as at first, they were ordered. Although one glass is 
worn at 90° and the other at 180°, they have given her entire 
relief from her asthenopic symptoms. I have seen the patient 
frequently since, and she continues to wear the glasses con- 
tinuously and with comfort. 

Case LII. Simple myopic astigmatism in one em\ and simple 
myopia in the other; Asthenopia; Relief with glasses. — May 6, 



130 ■ THE REFRACTIOX OF THE EYE 

1896, E. D., aged thirty-two, in good health, but has noticed 
since boyhood that he could not see quite so well as his com- 
panions when looking at distant objects. For the last six 
months he has experienced pains in the eyes and some frontal 
headaches after using his eyes for close work for any consider- 
able length of time. Some slight redness of the lids present, 
also produced by close use of the eyes. He is not of a myopic 
family, although he has one brother who has myopic astigma- 
tism of small amount. The patient is of the o^^inion that both 
he and his brother acquired most of their eye trouble from 
close application to books, as neither were compelled to wear 
glasses until near thirty years of age. 

OpTithalmometer . — Astigmatism with the rule, 1.25 D., axis 
90°+ or 180°- right eye; .50 D., axis 90°+ or 180°- left eye. 

Test cards and trial lenses. — 

R. y. = II - : -II _ W. - .75 D. cyl. 180°. 
L. Y. = f|-:f|-W.-.75D. 

Reads Jaeger No. 1, 41 to 20 inches. 

Ophthalmoscope. — Myopia ID. at 90° and emmetropia at 
180° right eye; myopia ID. left eye. There is a crescent of 
choroidal pigment at the temporal side of the disk in the right 
eye. 

Second test : the patient accepted the same glasses as at 
first, and they were ordered for constant wear. This patient 
has been under constant observation for more than two years, 
and the glasses have been worn with entire comfort. 

I am of the opinion that had there been no astigmatism 
in the right eye, but a simple myopia, as in the left eye, 
no glasses would have been required at all, as .75 D. to 1.50 D. 
of simple myopia rarely calls for a glass, unless the patient 
wishes to see very clearly for the distance. Very small 
amounts of myopic astigmatism, even so little as .25 D., in 



ILLUSTRATIVE CASES 131 

exceptional cases when associated with myopia and with slant- 
ing axes, may give rise to asthenopia and call for correction, 
as is shown by one or two cases reported in the following 
chapter. 

Case LIII. Corneal astigmatism with the rule^ .50 D. ; 
Patient accepts simple spherical glasses of high power for 
'distance^ and weaker for reading ; The rule for giving two 
pairs of glasses in high degrees of myopia considered. — Feb- 
ruary 26, 1895, I. G., aged thirty-two years, in good health, 
has had poor vision as long as he can remember, that is, from 
«arly childhood. No pain in the eyes or headaches are com- 
plained of — simply poor sight. 

Ophthalmometer. — Astigmatism with the rule, .50 D., axis 
90° -I- or 180°- in each eye. 

Test cards and trial lenses. — 

^' ^ • ~ 200 • 50 ^^ ' ^^ ^' 

L V — 1-^ -sow — 11 D 

-^' ^ • — 200 • 30 ^'^ • J-J- -L'. 

Reads Jaeger No. 1 at 8 inches, with — 11 D. right eye 
and — 8 D. left eye. 

Ophthalmoscope. — Myopia 15 D. right eye, myopia 12 D. 
left eye. Excessive pigmentation (choroidal tigre) in each 
eye, but no staphyloma in either. Vitreous clear in both. 

On a second test, the patient accepted the same glasses, 
both for the distance and the near point, as at the first test, 
and they were ordered. 

The corneal astigmatism of half diopter in this case was 
neutralized by the lenticular astigmatism, the usual amount of 
neutralization, and left it as simple myopia to deal with. This 
myopia was of so great an amount, however, that two pairs of 
glasses had to be prescribed, — one for distance and the other 
for reading, — and not, as it will be noted, on account of pres- 
byopia, for the patient Avas but thirty-two years of age. This 



132 THE REFRACTION OF THE EYE 

leads me to deal in a brief manner with the rule of procedure 
in such cases. 

If the myopia is of 8 D. or less, as a rule, the patient will 
need but one pair of glasses, which can be used both for the dis- 
tance and the near point. If the patient has worn glasses from 
early childhood, this one pair is usually sufficient ; for, having 
worn the glasses steadily, and thereby kept the eye corrected^ 
both for far and near work, the ciliary muscle has been devel- 
oped. On the other hand, in patients who have not come to 
the use of glasses till later in life (fifteen to twenty years of age), 
or have worn only partial correction, — say of myopia of 12 D. 
only 8 D. for the distance, and no correction for the near pointy 
— such patients will not tolerate the distance glass for constant 
wear. This is because the ciliary muscle has not been devel- 
oped, the work having been taken from it by the patient tak- 
ing off his glasses and bringing his work close to him at the 
focus, punctum remotum^ of his myopic eye. In this way no ac- 
commodative effort is necessary ; the ciliary muscle remains pas- 
sive, and does not develop. In such cases, the reading glasses 
have to be made weaker, just as in the higher grades of myopia. 

In high degrees of myopia, 8 D. or over, my rule of 
procedure is to find the glasses which give the best distant 
vision, as in other cases. If the glasses accepted are not 
higher than 10 or 12 D., and there are no pathological changes 
in the fundus of the eye of a serious nature, especially if the 
patient has been wearing nearly his full correction before, I 
prescribe these glasses for distant vision. In myopia of higher 
degree than this, the patient will not accept his full correction 
even for the distance, except for very brief periods at a time. 
In such cases, the full correction may be prescribed to be used 
in a lorgnette, while the glasses that are to be worn constantly 
for the distance must be made weaker. The amount of the 
reduction depends on the strength of the glasses the patient 
has previously worn, the age of the patient, and the condition 



READING GLASSES m HIGH DEGREES OF MYOPIA 133 

of the fundus of the eye. Roughly speaking, we would say 
that a myopia of 14 D. should wear about 12 D. as a constant 
distance glass ; a myope of 16 D. a 14 D. ; a myope of 18 D. a 
15 D. ; and a myope of 20 D. a 16 D. glass, and so on. There 
are numerous exceptions to this. It is rare to encounter 
myopia of over 25 D., though cases of as high as 40 D. have 
been reported at the New York Ophthalmological Society,^ 
and without conical cornea. 

To get the correct reading glasses in these high degrees of 
myopia, after having found the glasses I want him to wear con- 
stantly for the distance, I divide the number of inches at which 
the patient wishes to read, or sew, or work, into 40, in order 
to reduce it to diopters, then subtract the quotient from the dis- 
tance glasses. 2 The result is the number of the glass that the 
patient will usually accept for his close work ; but a reduction 
may have to be made in their strength if the patient has not 
worn glasses for a long time. To give an example, in the last 
case reported, the patient accepted — 14 D. right and — 11 D. 
left eye. He wanted a glass to read with comfortably at about 

1 Webster. 

2 Eorty is the number of English inches it takes to make a meter, and as 
my trial lenses are ground after the English inch (also numbered in diopters), I 
reckon in that system. Whereas, had my trial lenses been numbered after the 
French system, I would have used 36, the number of French inches it takes to 
make a meter. 

All trial cases were formerly marked in the inch system. For example, a 
glass of 10-inch focus would be marked ^, one of 40-inch focus, ^, etc. But 
as confusion was caused by the difference in length of the English and French 
inches, the dioptric or metric system of numbering was introduced. 

In the dioptric system of numbering, the meter is taken as the unit of 
measure. For example, a glass that will focus parallel rays of light at a distance 
of one meter is marked one diopter (1 D. thus) ; a glass that f ocusses the same 
rays at half a meter would have to be twice as strong, and is marked 2 D. 
A glass that f ocusses rays at two meters' distance would be marked .50 D., 
or half a diopter. The numbering goes on in an inverse ratio, for the shorter 
the focus the stronger the glass, necessarily. The metric or dioptric system of 
numbering is much better than the inch system, for a meter is a meter the world 
over, while inches of different peoples vary in length from each other. 



134 THE REFRACTION OF THE EYE 

i of a meter, or 13 inches. ^ Forty divided by 13 gave 3 D. in 
round numbers, which, subtracted from the distance glasses, 
gave — 11 D. right and — 8 D. left, for his reading glasses, 
which were prescribed. 

Again, say in the above case, the patient wished to read at 
10 inches. Divide 40 by 10, which will give 4 D. ; subtract 
this from the distance glasses, and we have — 10 D. right and 
— 7 D. left, for near work. Or, say the patient wanted to play 
the piano, or use his eyes for other occupation that would re- 
quire good vision at a distance of 20 inches ; divide 40 by 20, 
subtract 2D., the quotient, from the distance glasses, and we 
would have, in the above case, — 12 D. right and — 9 D. left, 
for the near work ; and so on. 

It should be borne in mind here, as, indeed, it should be at 
all times in fitting glasses, that all eyes are not alike in their 
working capacity, and will not conform, in exactly the same 
way, to any set standard or rule. This does not mean that we 
should not have a rule at all, but that we should have enough 
intelligence to vary the rule to suit the case^ and not try to make 
every case fit some cast-iron rule. 

In some cases, for the near point, we have to subtract more 
from the distance glasses than we have indicated here, and in 
some cases less. The power of convergence has something to do 
with it ; the strength of glasses that the patient has previously 
worn, the age of the patient, also, all have to be taken into 
consideration when giving reading glasses to a myope. Indeed, 
Landolt has laid it down as a general rule, in all degrees of 
myopia, " that a myope must be prohibited from wearing a con- 
cave glass for any distance at which he can see clearly without 
accommodation. "2 For example, a myope of 2 D. should not 

1 In order to get inches into diopters, divide them into 40 if using the Eng- 
lish inch, or into 36 if using the French inch, and vice versa. For example 
(English inch), a 10-inch glass is equal to 4 D., and a 4 D, = 10-inch glass ; a 
20-inch glass = 2 D., and a 2 D. glass = 20 inches, etc. 

2 Landolt, The Befraction and Accommodation of the Eye, p. 490. 



READING GLASSES IN HIGH DEGREES OF MYOPIA 135 

have any glass at all for distances under 20 inches, because his 
punctum remotum is at 20 inches, and he can see clearly without 
them up to that point. I believe it is a good plan myself, how- 
ever, in all cases of myopia under 8 D., who are compelled to 
wear glasses for the distance, to keep the glasses on all the 
time, unless troublesome asthenopia results ; then the distance 
glasses should be weakened according to the rule laid down 
above; or, if only of moderate strength, 3 or 4 D., taken off 
altogether for reading unless there is astigmatism present, when 
only the cylindrical part of the glass should be left on for read- 
ing and close work. The reason that I prefer to leave the dis- 
tance glasses on for near work in such cases is : first, to exercise 
and develop the ciliary muscle ; second, to render the eye em- 
metropic for all distances, and thus keep up the proper relation 
between accommodation and convergence ; third, because it is 
less trouble to keep the glasses on all the time than to be taking 
them off and putting them on frequently. Of course, in very 
high degrees of myopia, two pairs of glasses have to be resorted 
to, and sometimes three, if we include the lorgnette which they 
sometimes use for only a few moments. In cases of high degree 
of myopia, it is not always, in fact, it is never, simply a ques- 
tion of glasses, especially where progressive or malignant myopia 
is to be dealt with. In such cases, a general hygienic regime 
has to be followed, so far as the eyes are concerned, and the 
constitution built up with tonics. All close work with the ej'es 
must be prohibited, shaded glasses worn, local blood-letting 
practiced, the patient made to exercise and take the proper 
amount of rest, and so forth. In fact, the general condition of 
the patient should be brought up to the best. Unfortunately, 
such cases often occur in childhood, when the patient is try- 
ing to pursue his studies. It is unnecessary to say that such 
patients must be taken out of school, because close application 
to books always makes the mj^opia Avorse. 

In cases of high degrees of myopia, not malignant in char- 



136 THE REFRACTION OF THE EYE 

acter, that is, with healthy fundi, or, at most, with only a 
slight posterior staphyloma, and with but little tendency to 
increase, it is well for the patients to use the eyes as little as 
possible, and only with good light. In order to prevent strain- 
ing the eyes, these patients often acquire the practice of using 
but one eye at a time, especially for near work, pulling off the 
glasses and bringing the print up to the focus (^pmictum remo- 
turn) of the eye he uses. In this way he uses no accommoda- 
tion, and, at the same time, the images are much larger for the 
eye without the strong myopic glasses, which always make 
objects look much smaller. The eye that is not used usually 
swings out, that is, diverges. Where the eyes are sound, how- 
ever, I always encourage the use of glasses, and, in that way, 
give the stimulus to binocular vision both for the distance and 
for the near point. A divergent squint is sometimes prevented 
in this way, just in the same way as a convergent squint is 
sometimes prevented, and even cured in young children after 
once having appeared, by wearing plus glasses. 

The following case of moderate degree of myopia in 
one eye, and only a small amount in the other, with a ten- 
dency to, and, at times actual, squint outward, is a case in 
point. 

Case LIV. Myopia of moderate amount in one eye and 
small amount in the other ; Occasional divergent squint; Astheno- 
pia ; Relief of the squint and asthenopia with correcting glasses. — 
January 4, 1898, Miss E. M. L., aged twenty-one years, in 
good health, has been near-sighted in the right eye since a 
child, her family have noticed at times, when she was looking 
in the distance, that the right eye would turn outward. With 
close attention, however, the eye would turn back, and not 
squint. When she reads at night, the eyes tire, but there is 
little pain in them, and she rarely has headaches. 

The ophthalmometer showed a small amount of corneal 
astigmatism iu each eye; and, on the first test, the patient 



ILLUSTRATIVE CASES 137 

accepted compound glasses, but, on the second test, simple 
myopic spherical glasses gave the best vision. 

Ophthalmometer. — Astigmatism with the rule, .75 D., axis 
75°+ or 165°- right eye ; .25 D., 90°+ or 180°- left eye. 

Test cards and trial lenses, — 

R. Y. = 2'A 'U-^'- 4.50 D.-.50 D. cyl., 165°. 
L. V = 1^ - : |-§ W.- .25 D.-.25 D. cyl., 180°. 

Reads Jaeger No. 1, 3 to 12 inches right eye, and from 5 to 
25 inches in the left eye. Unless she looks at the point atten- 
tively, the right eye turns outward for the near point ; also, 
when looking in the distance, unless she is attentive, the right 
eye swings outward. 

Ophthalmoscope. — Myopia 5 D. right eye; myopia 1 D.(?) 
left eye ; normal fundi. 

On account of a mild conjunctivitis, alum was applied to 
the lids, an astringent wash prescribed, and the patient directed 
to come again in a week for a second test. This seemed advis- 
able, because there were unmistakable signs of spasm of accom- 
modation during the subjective test. The retinoscopic test 
was unsatisfactory. 

Second test : the ophthalmometer gave the same reading 
as at the first test. 

R-V. = A\:ff W.-5 D. 
L-V. = 1^ :|f + W.- .50 D. 

The ophthalmoscope and retinoscope both confirmed the 
subjective test. The tendency to spasm of accommodation had 
subsided. I ordered for constant wear —1.50 D. rio-ht and a 
plain glass left. The patient has been under observation for 
a period of eight months. She has single binocular vision both 
for near and far with the glasses, is entirely free from astheno- 
pia, and is much pleased with the result. 



138 THE REFRACTION OF THE EYE 

Case LV. Myopic astigmatism of moderate amount; Pres- 
byopia; Simple minus cylindrical glasses for the distance, and 
cross-cylindrical glasses for reading. — May 28, 1897, L. J., aged 
forty-five years, iu good health, has worn glasses since nineteen 
years of -age, which are all right for the street now, but have 
not been comfortable for reading purposes for the last two 
or three years. Her distance glasses are — 2. D. cyl., 180°, in 
each eye. 

Ophthalmometer. — Astigmatism with the rule, 2.50 D., axis 
90° + 180°- in each eye. 

Test cards and trial lenses. — 

R. V. = f^ - : 1^ W. -2D. cyl., 180°. 
L. V. = ||-:|^W.-2D. cyl.,180°. 

Reads Jaeger No. 1 from 7 to 18 inches, with + 1 D. 
spherical glass added to the distance glasses. 

Ophthalmoscope. — M. 2D. in the vertical meridian, and 
emmetropia in the horizontal meridian in each eye. 

The patient was allowed to continue the minus cylindrical 
glasses for distant vision, and + ID. — 2D. cyl., 180°, was 
ordered for each eye for reading purposes. This glass in 
effect is the same as cross-cylinders, that is, -h ID. cyl., 
90° - 1 D. cyl., 180°. But, before going into details of the 
transposition of glasses that is made necessary in cases of 
myopes who have become presbyopic, I wish to report two 
other cases of simple myopic astigmatism in presbyopes, in 
order to have two or three cases for illustration, rather than 
one. 

Case LVI. Simple myopic astigmatism with the rule; Pres- 
byopia; 3Iinus cylindrical glasses for the distance, and plus cylin- 
drical glasses for the near work. — August 16, 1896, Samuel T., 
aged forty-six, in good health, has worn glasses since twenty 
years of age, on account of near-sightedness. For the past 



ILLUSTRATIVE CASES 139 

two years he has experienced some trouble in his near work, 
especially when reading at night. 

Ophthalmometer. — Astigmatism with the rule, 1.50 D., axis 
90° + or 180° - in each eye. 

Test cards and trial 



^' V- = 1^ • ft W. - 1 D. cyl., 180°. 
L- V. =1^ : fl W. - 1 D. cyl., 180°. 

Reads Jaeger No. 1 from 8 to 20 inches, with +1 D. sphere 
added to the cylindrical glasses. 

Ophthalmoscope. — M. 1 D. in the vertical meridian (90°), 
and emmetropia in the horizontal meridian (180°) in each eye. 

The patient is now wearing— ID. cyl., 180°, exactly the 
same glasses he accepted in this test, and they were ordered 
continued. For reading glasses -fl D. cyl., 90°, was ordered 
for each eye. 

Case LVII. Simple myopic astigmatism ivith the rule in one 
eye and against the rule in the other ; Presbyopia ; Minus cylin- 
drical glasses for the distance and plus cylindrical glasses for 
reading. — October 10, 1896, Kate M., aged forty-one, in good 
general health, for the last year her eyes have given her a 
great deal of trouble for close work. The vision blurs, and the 
eyes and head ache after using the eyes. 

Ophthalmometer. — Astigmatism with the rule, 1 D., axis 
60° + or 150° — right eye ; astigmatism against the rule, 1 D., 
135°+ or 45°- left eye. 

Test cards and trial lenses. — 

R. V. = §^ : li W. - .50 D. cyl., 15°. 
L. V. = 1^ : li W. - .50 D. cyl., 45°. 

Reads Jaeger No. 1 at 8 inches, with +.50 D. added to the 
distance glasses. 

Ophthalmoscope.— M. 1 D. at 60° and Em. at 150° right 
eye; M. 1 D. at 135° and Em. at 45° left eye. 



140 



THE REFRACTION OF THE EYE 



On a second test, this patient accepted the same glasses, 
both the distance and the near, as at the first test. As her 
eyes gave her no special trouble for the distant vision, I pre- 
scribed only the reading glasses, +.50 D. cyl., 60° right, and 
4-.0OD. cyl., 135°left. 



150, 




135" 




R. E. 



L. E. 



Fig. 64. 



It will be noticed in this case that although the instrument 
reads astigmatism against the rule, 1 D., in the left eye, the 
patient accepts only .50 D. cyl., the same amount as the other 
eye, wherein the instrument reads astigmatism with the rule, 
1 D. This makes me repeat what I have alread}^ pointed out 
above, that when the chief meridians are exactly at 45° and 
135°, as in the left eye in this case, the terms "with the rule " 
and " against the rule " do not strictly hold. This should be 
borne in mind, therefore. 



Presbyopic Glasses for Myopes 

For the benefit of students and beginners in the practice of 
ophthalmology, I think it well at this place to consider briefly 
the influence of presbyopia as it affects the reading glasses. 



PRESBYOPIC GLASSES FOR MYOPES 141 

especially in myopes. It is, as a rule, an easy matter to give 
the correct reading glasses to an emmetropic, or a hyper- 
metropic individual. To do so it is necessary only to add 
a certain increase to the distance glass (if the patient accepts 
any distance glass), usually about -|- 1 D. spherical glass for 
each five years of age after forty years of age, to get the cor- 
rect glasses. A better standard, perhaps, is the one of giving 
the glasses that the patient can read with, with comfort, at 
13 inches, or with effort at 8 inches. As stated above, this 
requires about + 1 D. for each five years after forty years 
of age ; but some patients will accept but .50 D., while others 
will require as much as 1.50 D., or even more in exceptional 
cases, for each five years after forty years of age, in order to 
read with comfort (Jaeger No. 1) at 13 inches, or with effort 
at 8 inches. For instance, to give an example or two, an 
emmetrope at forty-five years of age should wear about -\- 1 T>. 
for reading, and at fifty years of age + 2 D., and at fifty-five 
years -|- 3 D., and so on. The variation from this is easily 
ascertained by having the patient read the Jaeger No. 1 type 
at 8 inches. The glass that is required to enable him to 
read this type at that distance, with effort, is the correct 
^lass (Bonders). 

Again, a hypermetrope who is wearing -1- 2 D. for the dis- 
tance should wear about + 3 D. for reading when forty-five 
years of age, and + 4 D. at fifty years, etc. Or if the patient 
is wearing compound hypermetropic glasses for the distance, 
it is only necessary to add to the spherical part of the glass the 
usual amount of -f 1 D. for each five years, in order to get the 
correct reading glasses, leaving the cylindrical part as it is. 

In myopic astigmatism the fitting of presbyopic glasses is 
not so easy, especially for the beginner ; for the changing from 
minus cylindrical glasses to plus, with change of axis, though 
apparently very simple by the algebraic equation, is not, as a 
rule, quickly grasped by the student. For this reason I not 



142 THE REFRACTION OF THE EYE 

only teach them the method by algebraic equation, but draw- 
diagrams of the eye shoAving the focus of the two chief 
meridians for the distance, and then the change of focus 
brought about by presbyopia, calculating on the basis of 
+ 1 D.i for each five years. This places before the eye of 
the student the change of focus of each meridian, and at the 
same time indicates the nature and strength of the glass neces- 
sary for the near w^ork of the patient. It has the further 
advantage of making the student think of the eye under obser- 
vation, and does not let him decide the matter by an abstract 
algebraic equation. This may seem of little importance to those 
who do not instruct ; but, I am sure, to teachers, this concrete 
way (wdth the assistance of diagrams) of imparting knowledge 
will at once be apparent as the better method of teaching. 

Now, in simple myopia without astigmatism, the fitting of 
presbyopic glasses is not difficult, because, adding + 1 D. 
(algebraically) for each five years of age after forty to the 
distance glass, we easily get the right glass for reading or 
w^orking purposes. To take an example, say the patient wears 
— 2D. for distant vision, and is forty-five years of age. Add 
-1- 1 D. to — 2 D., and we have left —ID., which would be 
the reading glass. At fifty years of age the patient would 
be 2 D. presbyopic. Plus 2 D. added to —2D. equals 0, that 
is, they exactly neutralize, so that the patient would need na 
reading glass at this age. At fifty-five years of age, + 3 D. 
added to —2D. would give + 1 D., which would be the cor- 
rect glass. 

In cases of simple myopia of high degree, wdiere tw^o pairs 
of glasses are worn, in giving presbj-opic glasses, w-e add the 
presbyopic glass to his weaker glasses (the glasses that he uses 
for near work), and leave the distance glass as it is. Neverthe- 
less, even this distance glass of high myopes has to be w^eak- 
ened as the patie^it advances in age ; for even the static 

1 Of course the 8-inch test for Jaesrer No. 1 is the final decisive test. 



TRANSPOSITION OF GLASSES 143 

refraction of the eye begins to get weaker at fifty years of 
age, and at eighty years of age has actually decreased about 
2.50 D. In Case LIU, for instance, where — 14 D. right and 

— 11 D. left were ordered for the distance glass, and —11 D. 
right and — 8 D. left for reading, when this patient reaches 
forty-five years of age he should wear, on account of his 1 D. 
of presbyopia, + 1 D. added to — 11 D. right, and + 1 D. 
added to — 8 D. left, which would give for reading glasses 

- 10 D. right and - 7 D. left. At fifty years of age, -f 2 D. 
added to — 11 D. and — 8 D. would give — 9 D and — 6 D., 
respectively, as the reading glass, and so on. 

On account of the decrease of the static refraction of the 
eye, his strong distance glasses, — 14 D. right and — 11 D. 
left, should be decreased in strength, and much more than is 
indicated by the tables of scales as given in the various text- 
books. At the age of sixty, for instance, the static refraction 
has decreased .50 D., yet a much greater reduction in the 
strength of the distance glasses has to be made than this 
amount where the myopia is of high degree. 

In myopic astigmatism in presbyopes we have to deal with 
the transposition of cylindrical glasses, and it is not so easy as 
in cases of simple myopia and spherical glasses. 

I will take some of the cases reported in this chapter as 
illustrative examples. In Case LVI, the patient accepted for 
the distance — ID. cylindrical glass, axis 180°, in each eye. 
He was forty-six years of age, and required a reading glass. 
He accepted + 1 D. cyl., 90°, in each. A + 1 D. spherical 
glass added to — 1 D. cyl., 180°, would be in effect + 1 D. 
cyl., 90°. As the latter glass was simpler, lighter, and cheaper, 
it was prescribed. A glance at Fig. QS will show the change 
in focus brought about by the 1 D. of presbyopia. 

The 1 D. of myopia in the vertical meridian is just neutral- 
ized by the 1 D. of presbyopia ; Avhile the horizontal meridian, 
which was emmetropic, becomes in effect hypermetropic 1 D., 



144 



THE EEFRACTIOI^ OF THE EYE 



by reason of the 1 D. of presbyopia. In other words, the eye 
for reading purposes at that age is converted into a simple 
hypermetropic, astigmatic eye, and requires a simple + 1 D. 
cyl., 90°, to correct same. 

At fifty years of age the patient would require for a read- 
ing glass + 1 D.s + 1 D. cyl., 90° ; for, on account of 2 D. 
of presb3^opia, the focus in the vertical meridian, for reading 
purposes, has receded behind the retina, as well as the focus in 
the horizontal meridian (in the vertical meridian 1 D. and in 

90° 





DISTANCE 



NEAR 



180' 




FiQ. 65. — Showing focuses of chief meridians for distant vision and for near vision at 
the age of forty-five years, iu simple myopic astigmatism of 1 D. 

the horizontal meridian 2D.). A + 1 D. sphere corrects the 
vertical meridian and half the presbyopia of the horizontal 
meridian, the + 1 D. cyl., 90°, being required to complete the 
correction in the horizontal meridian. 

At fifty-five years of age, this patient would require 4- 2 
D.s -hi D. cyl., 90°, and so on, about -f 1 D. spherical glass 
extra for each five years being required to be added to the 
cylindrical glass. 

Take another example, suppose the patient accepts — 2D. 
cyl., axis 180°, for the distance, as in Case LV. At forty-five 



ILLUSTRATIVE CASES 



145 



years of age, this patient would be about 1 D. presbyopic, and 
should wear for reading + 1 D.— 2 D. cyl., 180°, in each eye ; 
or, if we chose, we could give cross-cylinders, e.g.^ +1 D. cyl., 
90°— 1 D. cyl., 180°, which glass is exactly the same in effect 
as the sphero-cylindrical glass -}- 1 D. — 2 D. cyl., 180°. 

To make this perfectly plain, we will give a diagram of the 
eye, showing, first, the foci of the two chief meridians for dis- 
tant vision ; and, second, the foci as affected by the 1 D. of 
presbyopia at forty-five years of age. 




DISTANCE 



NEAR 



180' 



180 




Fig. 66. — Showing focuses of the chief meridians in simple myopic astigmatism of 
2 D. for distant vision and for near vision at the age of forty-five years. 

The 1 D. of presbyopia neutralizes 1 D. of the myopic 
astigmatism in the vertical meridian (leaving ID. of it uncor- 
rected), and at the same time renders the horizontal meridian 
(which is emmetropic) presbyopic, or in effect hypermetropic 
1 D. Thus the eye for reading purposes is mixed astigmatic, 
since it focusses rays of light in front of the retina in the verti- 
cal meridian, and back of the retina in the horizontal meridian. 
Now, to correct this we can give either the cross-cylindrical 
glasses, + 1 D. cyl., 90° -ID. cyl., 180°; or we can give 
sphero-cylindrical glasses, -\- 1 D. — 2 D. cyl., 180°. In the 



146 THE REFRACTIOX OF THE EYE 

first instance, with the cross-cylinders, the + 1 D. cyl., 90°, 
corrects the 1 D. of presbyopia in the horizontal meridian, and 
the —ID. cyl., 180°, corrects the one remaining diopter of 
mj^opic astigmatism in the vertical meridian. In the second 
instance, with the sphero-cylindrical glasses, the + 1 D. sphere 
corrects the 1 D. of presbyopia in the horizontal meridian, and 
at the same time renders the eye myopic to that extent in the 
vertical meridian ; and the increase of myopic astigmatism by 

1 D. in addition to the 1 D. already present makes it necessary 
to give —2D. cyl., 180°, instead of — 1 D. cyl., as when 
cross-cylinders were prescribed. In other words, we have to 
neutralize the effect of the plus spherical glass in the vertical 
meridian. This, of course, makes a heavier glass than a cross- 
cylindrical. The field of vision also is made somewhat smaller 
by the sphero-cylindrical glasses than by the cross-cylindrical. 
But both of these objections are of but little importance in 
mixed astigmatism of low degree, as in the present instance. 
When the mixed astigmatism is of large amount, cross-cylin- 
drical glasses are to be given in preference to sphero-cylindri- 
cal, as a general rule. 

At fifty years of age, this patient (Case LV) would 
require a simple + 2 cyl. axis 90°, because at this age the 

2 D. of myopic astigmatism in the vertical meridian is just 
neutralized by the 2 D. of presbyopia, while the emmetro23ic 
horizontal meridian is rendered 2 D. presbyopic (or hyperme- 
tropic in effect), and requires the -f- 2 D. cyl., 90°, to correct 
same. At fifty-five years of age, the patient would wear 
-f- 1 D. 4- 2 D. cyl., 90° ; and at sixty years, -f- 2 D. -f- 2 D. 
cyl., 90°, and so on. 

For the transposition of glasses, made necessary on account 
of presbyopia, in compound myopic astigmatism, and in mixed 
astigmatism, suitable examples are given for illustration in the 
chapters on compound myopic astigmatism and mixed astig- 
matism, which immediately follow. 



CHAPTER YI 

COMPOUND MYOPIC ASTIGMATISM — ANTIMETROPIA — ILLUSTRA- 
TIVE CASES — ACCESSORY EFFECTS OF STRONG MYOPIC 
GLASSES 

In testing for glasses in compound myopic astigmatism, we 
"begin tlie test in exactly the same way as when testing for 
the glasses in simple myopic astigmatism. That is, we examine 
the eye first with the ophthalmometer to ascertain if there is 
any corneal astigmatism. Having found the amount and axis 
of the astigmatism, we next begin the subjective test with the 
trial case and test card. And here, and as a matter of fact in 
<all errors of refraction where astigmatism is present, we begin 
the test with weak plus cylindrical glasses, unless we know 
beforehand the nature of the error of refraction ; for the ex- 
amination with the ophthalmometer does not reveal the nature 
of the error of refraction, and plus glasses are begun with in 
order to avoid inciting a spasm of accommodation. ^ If the 
patient proves not to be hypermetropic, no harm is done and 
but little time lost. We then begin with weak minus cylin- 
drical glasses at the axis indicated by the ophthalmometer, and 
gradually increase their strength so long as they improve 
vision, being careful to stop with the weakest glass that gives 
the best vision. If the vision is not brought up to perfect, |^, 
with cylindrical glasses alone, we next add a weak minus 
spherical glass to the cylinder, and if it improves vision, 
gradually increase it in strength until the vision ceases to be 
improved. The weakest minus glasses that give the best 
vision are given. 

1 As explained in a previous chapter, if minus glasses are begun with they 
are often accepted, though the patient be hypermetropic. 

147 



148 THE REFRACTION OF THE EYE 

In very high degrees of myopia complicated with astig- 
matism, especially where the astigmatism is of small or only 
moderate amount, we have to correct part or most of the 
myopia before the cylindrical glass is appreciated when placed 
in front of the eye. Starting the test in the routine way in 
such cases, plus glasses would of course make the vision worse, 
and would be refused ; and minus cylindrical glasses, though 
accepted, would not appreciably improve vision. Notwith- 
standing the fact that the cylindrical glasses, as indicated 
by the ophthalmometer, do not appreciably affect the vision 
one way or the other, I leave them in the trial frames and add 
minus spherical glasses to them, rapidly increasing them in 
strength. If the poor vision is due to myopia, and no very 
serious fundus changes have taken place to cause amblyopia, 
the minus spherical glasses, which give the best vision, are 
soon found. When I have reached this point in the test, I 
then leave the minus spherical glasses in the trial frames and 
go back to the cylindrical glasses, increasing and diminishing 
them in strength alternately, to see if vision can be further 
improved ; for, with the myopia corrected, any change in the 
cylindrical glasses is more easily perceived. However, as 
above stated, where the myopia is large in amount, 8 D. or 
more, and the astigmatism small in amount, cylindrical glasses 
increase the vision very little when added to the spherical 
glasses, at times even when the astigmatism is as much as 2 D. 
In such cases, and particularly when the astigmatism is with 
the rule and exactly at 180°, it is often best to give simple 
spherical glasses alone, tilting them slightly on the horizontal 
axis, the upper part forward, to get the necessar}^ cylindrical 
effect. The patient will do this tilting for himself, if it is not 
done for him, after wearing them for a few weeks. 

The giving of a simple spherical glass and tilting it on the 
horizontal axis is, when it can be done, advantageous in three 
ways : first, it is a simple glass, and not a compound one ; 



ILLUSTRATIVE CASES 149 

second, it is a lighter glass ; and third, it is a cheaper glass 
than a compound one. 

We are to be guided in such instances (giving only spher- 
ical glasses where there is a large amount of myopia and 
only a small amount of astigmatism) by the increase of vision 
the cylindrical glass gives when added to the spherical glass. 
For example, say a patient accepts a — 10 D. spherical glass 
and his vision is brought up to J^ with it ; and by adding a 
— .75 D. cyl., axis 180°, the vision is increased to only -|-g — , 
or not one whole line. In such case I would not give the 
compound glasses, but the simple — 10 D., and tilt them 
slightly forward on the horizontal axis. 

Where the myopia is not large in amount (under 8 D.), and 
the astigmatism is moderate or small in amount, and when the 
vision is considerably improved by the correction of this astig- 
matism, it is best to give a compound glass. This is the more 
important if the axis of the astigmatism is off from 180°, for 
then it is difficult to get the proper cylindrical effect by tilting 
the spherical glasses. 

Where there are fundus complications, vision will not, as a 
rule, be improved much with any glass whatsoever. Moreover, 
if the myopia is of the progressive type, glasses are of second- 
ary importance ; for, in such cases, constitutional treatment 
and general hygienic conditions are much more to be consid- 
ered. The eyes should be given complete rest, and, if sensi- 
tive to light, shaded glasses should be worn. In cases of 
children with progressive myopia, they should be taken from 
school, or be allowed to go for only one or two hours a day ; 
for, if close application at books is persisted in, the eyes are 
irreparably injured by hastening the progress of the disease. 

Case LVIII. A typical case of compound mi/opic asficpna- 
tism ; Slight asthenopia; Vision brought up to perfects ||[-, with 
glasses. — April 4, 1897, C. A. B., aged twenty-seven years, 
consulted me four months ago on account of a chalazion on the 



150 



THE REFRACTION OF THE EYE 



right upper eyelid, which was cured by incising and curetting. 
He comes now on account of poor vision, and for slight pain 
in the eyes, after using them for continuous close work. His 
vision has never been very good, and, until lately, he has been 
free from asthenopia. 

Ophthalmometer. — Astigmatism with the rule, 2.50 D., 
axis 90°+ or 180°— in each eye. 

Test cards and trial lenses. — The vertical lines on the 
clock-dial are seen plainest, though none of them are seen 
very plain. 

^' ^' = tA • U +^^- - 3-50 D- - 2.50 D. cyl., 180°. 
L- ^' = 2W • II +W.- 3.50 D.- 2.50 D. cyl., 180°. 

Reads Jaeger Ko. 1 from 4 to 20 inches. 

Ophthalmoscope. — M. 5 D. in the vertical meridian (90°), 
and M. 3 D. in the horizontal meridian (180°), in each eye. 
The fundus in each eye is normal. 




Fig. (J7. 



Five days later a second test was made. The ophthalmo- 
scope and ophthalmometer showed the same condition as at the 
first test. 



ILLUSTRATIVE CASES 151 

Test cards and trial lenses. — 

^' ^' = iA : 1^ 4- W. - 3 D. - 2.25 D. cyL, 180°. 
L. V. = 2V^ : 1^ + W. -3D.- 2.25 D. cyL, 180°. 

This last glass was ordered. It has given relief from his 
asthenopia, and is worn with great satisfaction and comfort. 
I may say that my routine method was followed in testing this 
case. Plus cylindrical glasses were first tried ; these were 
rejected. Then minus cylindrical glasses were tried, and the 
patient accepted a — 2.25 D. cyl., 180°, with improvement in 
vision ; but, as it was not brought up to normal vision, minus 
spherical glasses were added to the cylindrical, the strength 
being gradually increased till — 3D. was reached. As this 
combination of glasses was the weakest minus glass that gave 
him the best vision, it was ordered. 

The same routine procedure was pursued in all of the fol- 
lowing cases. 

Case LIX. Compound myopic astigmatism^ where the myo- 
pia is cofisiderable in amount and the astigmatism small in 
amount ; Patient is luearing spherical glasses ; Slight asthenopia^ 
with poor vision ; Relief with glasses. — February 7, 1895, Annie 
C, aged twenty-eight years, in good general health, consulted 
me on account of poor vision and occasional headaches over the 
brows. She comes of a myopic family. She fitted herself to 
glasses sometime ago (— 5 D. sphere each eye), but they have 
not given relief. 

Ophthalmometer. — Astigmatism with the rule, 2 D., axis 
80°+ or 170°- right eye ; 2 D., axis 100°+ or 10°- left eye. 

Test cards and trial lenses. — 

^' ^' = 2*0 • M W.- 5 D.- 1.50 D. cyl., 170°. 
L- V. = 2W • U ^^^' - 5 D. - 1.50 D. cyl., 10°. 

Heads eJaeger No. 1, 5 to 15 inches. 

Ophthalmoscope.— M. 7 D. at 80° and 5 D. at 170° right 
eye ; M. 7 D. at 100° and 5 D. at 10° left eye. 



152 



THE REFRACTION OF THE EYE 



There is a narrow crescentic staphyloma to the temporal 
side of the disk in each eye. 





R. E. 



Fig. 68. 



L. E. 



On a second test the patient accepted the same glasses as at 
first ; they were ordered, and have given satisfaction for more 
than three years. 

Case LX. Compound myopic astigmatism^ the myopia being 
large in amount^ while the astigmatism is small in amount. — 
June 15, 1894, Miss E. E. D., in fairly good health only, con- 
sulted me on account of poor vision. There is no asthenopia. 
She comes from a myopic family, and her sight has been poor 
from childhood. 

Ophthalmometer. — Astigmatism with the rule, 2.25 D., axis 
100°+ or 10°- right eye ; 2.25 D., axis 75°+ or 165°- left eye. 

Test cards and trial 



R. V. 



200 • TO 



: 2^ ^v, _ 16 D. - 1.25 D. cyl., 10°. 



^' **200*70 ^^ ' 



16 D. - 1.25 D. cyl., 165°. 
Reads Jaeger No. 1 at 7 inches, with — 10 D. spherical 



glass on each eye. 



ILLUSTRATIVE CASES 153 

Ophthalmoscope. — Myopia of 16 D. in each eye. There is 
a large posterior staphyloma in each, but there is little cho- 
roidal change. 

A second test resulted in the patient accepting the same 
glass as at first ; ordered, — 16 D. for the distance, in the form 
of a hand-lorgnette, and — 10 D. for close work. 

In this case the myopia was so great and the amblyopia so 
marked that the cylindrical glass improved vision but little, 
so it was not added to the spherical glass, especially as the 
latter was already very heavy. Moreover, it many times hap- 
pens, in these cases of high degree of myopia, that the patient 
is not able to wear the full correction, even in the street. In 
such instances we must reduce the power of the glass if we 
give it for constant wear ; or give it full strength in a lorg- 
nette, to be used for only a few moments at a time, when 
the patient wishes to see distinctly. 

Patients who have worn glasses from childhood can wear 
much nearer their full correction, in these high degrees of 
myopia, than those who have worn very weak glasses, or none 
at all till later in years. The reasons for this are : first, in 
those who wore glasses that corrected most of their myopia 
from early childhood, the ciliary muscle had to be used when 
looking close at hand, and in this way it was developed ; and 
strong glasses can on this account be worn without fatigue. 
But in those who have not worn anything like their full cor- 
rection, or have worn no glass at all, the ciliary muscle remains 
undeveloped from non-use ; and when strong glasses are pre- 
scribed, requiring the use of the ciliary muscle for near work, 
the eyes easily tire, because of the very weak ciliary muscle. 
Second, the distorting and minifying effects of strong myopic 
glasses are not noticed so much by a child in early life, and 
he grows accustomed to the effects as natural ones ; while the 
effects of such glasses prescribed later in life are very annoy- 
ing, so much so, that in some cases patients will not tolerate 



154 THE REFRACTIOiSr OF THE EYE 

anything like the full correction. The prismatic action and 
minifying action of strong minus glasses have to be taken into 
consideration, and a reduction in the strength of the glass has 
to be made to secure comfort for the patient. I have in mind 
one patient who accepted — 17 D. and saw J^ on Snellen test 
cards with the same, yet was unable to, or rather would not, 
wear them on the street, because, as she said, she could not 
recognize her intimate friends in the street with them on, on 
account of the distortion and contraction of their features. 
She had been wearing — 10 D. before, and — 12 D. was the 
strongest she could wear with comfort, though she saw much 
worse with this than with the — 17 D., so far as the test cards 
were concerned. In these very high degrees of myopia, there- 
fore, there is no strict rule by which we may go, and we have 
to seek the comfort of the patient. I usually reduce the glass 
from the full correction, even for street wear, and give a still 
weaker glass for reading. If the patient desires a full correc- 
tion, I give it in a lorgnette, which can be used for a few 
moments at a time. 

I have prescribed as high as — 22 D., on one occasion, for 
a man who had about 26 D. of myopia. He had only one eye, 
however, and the troublesome question of the relation between 
convergence and accommodation was eliminated in his case. 
Not only did this glass minify objects in a marked degree, but 
when his eye was looked at through the glass, it made the eye 
appear very small to the observer, in fact, almost like a bead. 

There is another point about cases of high degree of myopia, 
especially where there are fundus lesions, that I wish to call 
attention to here, and that is, that their vision seems much 
worse when the stomach is upset or their general condition 
much disturbed in any way. After they have quieted down, 
the vision comes up to what it was before the disturbance 
occurred and they are again happy, though much concerned 
about their sight at the time of the disturbance. If this point 



HIGH DEGREES OF MYOPIA 155 

is not borne in mind, we might be induced by the patient to 
change the glasses unnecessarily at such time. 

The general health of these patients should be looked after 
most carefully, outdoor exercise ordered, rest to the eyes en- 
joined, and close work for the eye for any considerable time 
prohibited. In school children especially, who show any ten- 
dency to progressive or malignant myopia, too much stress can- 
not be laid on the observance of general hygienic conditions, 
such as much out-of-door exercises, short hours of study, — 
and then under the most favorable surroundings, — good light, 
upright position of the child at desk, etc., and proper correction 
of errors of refraction. It is much better to let these children 
go through school with a little book learning, rather than to 
let them acquire knowledge, at the expense of eyesight, which 
they can never put into effect in after life. In fact, if it comes 
to a question of school education or eyesight, stop the child 
from school altogether ; at any rate, allow him the fewest of 
hours of study possible, and this time to be divided by short 
intervals, so as not to weary the eyes too much. 

Case LXI. Large amount of myopia tuith a moderate amount 
of astigmatism ivith the rule ; Axis of the astigmatism horizontal 
in one eye and off from the horizontal in the other ; Asthenopia ; 
Relief with glasses. — June 1, 1896, Katie McQ., aged thirty- 
one years, in good health, comes on account of poor vision and 
some asthenopic symptoms. She is now wearing — 9.50D.S 
right eye and — 9 D.s left eye. 

Ophthalmometer. — Astigmatism with the rule, 3D., axis 
105°+ or 15°- right eye ; 1.50 D., axis 90°+ or 180°- left eye. 

Test cards and trial lenses. — 

R- V. = Hts ■■ fi W. - 8 D. - 2.50 D. eyl., 15°. 
L- V. = ^A^ : If W. - 11 D. - 1 D. cyl., 180°. 
Reads Jaeofer No. 1 at 9 inches. 



156 THE REFRACTION OF THE EYE 

Ophthalmoscope. — M. 11 D. at 105° and 8 D. at 15° right 
eye ; M. 13 D. left eye. There is a small posterior staphyloma 
in the right eye, and a large one in the left, with spots of 
choroidal changes scattered over the fundus in each. 

Second test : the patient accepted the same glasses as at 
the first test, and these were ordered. 

In this case the vision w^as considerably improved by the 
addition of the cylindrical -to the spherical glasses, and the full 
correction was ordered to be worn constantly, although the 
myopia was large in amount in the left eye. The glasses were 
worn with perfect comfort. 

1 wish to emphasize a point in this case which has already 
been alluded to in this chapter in a general way, and that is, 
that the patient was able to wear these strong myopic glasses 
for near work with comfort. This is not always so, and in her 
case was due to the fact that she had worn almost full correc- 
tion for her myopia since a child ; and, having her myopia 
corrected for the distance, she was compelled to use her accom- 
modation for near points. In this way the ciliary muscle was 
developed, and when she came to full correction in after years, 
she was able to wear the glasses with comfort. 

Case LXII. Large amount of myopia; Small amount of 
astigmatism^ hut marked increase of vision hy its correction ; Full 
correction ivorn with comfort. — March 15, 1898, Rebecca G., aged 
seventeen, in good health, came to the clinic of Drs. Lewis and 
Van Fleet, at the Manhattan Eye and Ear Hospital, for glasses, 
on account of poor vision, and because the glasses she had were 
not satisfactory. She had glasses fitted first when ten years of 
age. These glasses were changed after five years' time for the 
glasses that she is now wearing, — 11 D. in each eye. 

Ophthalmoyneter . — Astigmatism with the rule, 2D., 90°+ or 
180°- each eye. 

^' ^' = 2*0 : f^ - W. - 13 D. - 1.50 D. cyl., 180°o 

L. V. = 2^0 : 1^ - W. - 13 D. - 1.50 D. cyl., 180°. 



ILLUSTRATIVE CASES 157 

Reads Jaeger No. 1, 5 to 15 inches. 

The cylindrical glasses increased the vision from |^ to |-^, 
a marked increase when we consider the amount of myopia 
present and the small amount of astigmatism. 

Ophthalmoscope. — Myopia 15 D. in each eye; also a small 
posterior staphyloma in each eye. 

Second test : the patient accepted the same glasses, and 
they were ordered for constant wear. Here again the glasses 
were very strong, but, as the patient had worn almost full 
correction for some time before, they were worn with entire 
comfort. 

Moreover, the cylindrical glasses, though small in amount 
and with axis exactly at 180° in each eye (for this reason, as a 
rule, their effect could easily have been gotten by tilting the 
strong spherical glass, —V6 D., slightly on the horizontal axes), 
were ordered in this case, because they so markedly increased 
the vision when added to the spherical glasses, and tilting of 
the spherical glasses did not give near so good vision. 

Case LXIII. Comjjound myopic astigmatism in one eye; 
Simple myopia of small a7nount in the other; Scopolamine used as 
a mydriatic. — October 13, 1894, Miss M. R., aged thirty-one, 
in good general health, consulted me for burning and itching 
in the eyes, and for a strained feeling in them after using them 
for close work. She is a stenographer, and her eyes have 
troubled her more or less for the last year. She has no head- 
aches, but there is a mild conjunctivitis present. 

Ophthalmometer. — Astigmatism with the rule, .75 D., axis 
90°+ or 180°- right eye ; .50 D., axis 90°+ or 180°- left eye. 

Test cards ajid trial lenses. _ — 

R. V. = 1^ : ff - W. - 1 D. - .25 D. cyl., 180°. 
L. V. =|^ + : If- W. - .50 D. 

Reads Jaeger No. 1, 6 to 15 inches. 

Ophthalmoscope. — M. 1 D. right eye ; INI. .50 D. left eye. 



158 THE REFRACTION OF THE EYE 

There was some redness and injection of the conjunctiva 
with some scattering granulations on the palpebral conjunc- 
tiva. On this account, and the weak minus glasses being 
accepted, I thought perhaps the apparent myopia, as observed 
by the ophthalmoscope and as manifested by the glasses 
accepted, was due to a spasm of accommodation, even though 
the patient accepted the same glass time and again during the 
examination. 

As the patient was in a hurry for the glasses, I instilled a 
solution of scopolamine (gr. i to §i), one drop in each eye, 
every five minutes, for six consecutive times, then waited one- 
half hour and tested, with the following result : — 

R. V. = -^0% • ft - ^^- - '^^ ^' - -50 ^' cyi-. 180°- 
L. V. = 3^0% : ff - W. - .25 D. - .25 D. cyl., 180°. 

The ophthalmoscope and ophthalmometer gave the same 
results as at the first test. 

Third test, three days later, when the patient was not 
under the influence of the mydriatic, resulted as follows : — 

R. V. = 1^ : ff - W. - .75 D. - .50 D. cyl., 180°. 
L. V. =|^:ft W.-.50D. 

Reads Jaeger No. 1, 6 to 15 inches. 

These last glasses were ordered, and have since been worn 
with comfort and satisfaction. 

In very low degrees of myopia it is impossible at times to 
decide with the ophthalmoscope or the retinoscope (without 
the use of a mydriatic) whether myopia is present or not. 
And the mere acceptance of minus glasses by a patient is not 
positive evidence by any means that myopia exists, as hyper- 
metropes, through spasm of accommodation, may, and often do, 
when improperly tested, accept minus glasses. Myopia of a 
low degree, 1 D. and less, rarely needs correction, unless there 
is a complicating astigmatism. 



ILLUSTRATIVE CASES 159 

Case LXIV. Compound myopic astigmatism in one eye; 
Simple myopic astigmatism in the other ; Asthenopia marked; 
Presbyopia. — June 5, 1894, Mrs. M. S. C, aged fifty, in good 
general health, comes on account of severe headaches and 
pains in the eyes, especially after using the eyes for close 
work. She has worn glasses for fifteen or twenty years, con- 
stantly for the last ten years. 

Ophthalmometer.- — Astigmatism with the rule, 4 D., axis 
125° + or 35° - right eye; 4 D., axis ^b° + or 145° - left 
eye. 

There is also some irregular astigmatism present in the 
right eye. 

Test cards and trial lenses. — 

R. V. = 2% : il + W. - 3.50 D. cyl., 35°. 

L. V. = ^\ : 1^ _ W. - 4 D. - 3.50 D. cyl., 145°. 

Reads Jaeger No. 1, 6 to 13 inches with + 2 D. added for 
the presbyopia, which in effect would be : + 2 D. — 3.50 D. 
cyl., 35° right, and -2D.- 3.50 D. cyl., 145° left. 

Ophthalmoscope. —M. 4 D. at 125° and Em. at 35° right 
eye ; M. 8 D. at B5° and 4 D. at 145° left eye. 

There are some diffuse corneal opacities on the cornea of 
the right eye, which accounts for the vision not being improved 
in that eye. 

A second test was made and agreed with the first, and 
both the distance and reading glasses were ordered. Both 
pairs of glasses have been worn with comfort. 

It is to the reading glasses I wish to call attention in this 
case. The patient, being fifty years of age, was presbyopic to 
the extent of 2 D. In the right eye she had simple mj^opic 
astigmatism, and either a cross-cylindrical or a sphero-cylin- 
drical glass could be given. If a cross-cylindrical glass, it 
would take the following form: + 2 D. cyl., 125° — 1.50 D. 
cyl., 35°. A glance at Fig. 69 shows why this is so. The 



160 



THE REFRACTIOX OF THE EYE 



emmetropic meridian at 35° becomes presbyopic by 2 D., and 
requires + 2 D. cylindrical glass at right angles to this meridian 
(at 125°) to correct it ; while the presbyopia of 2 D. neutral- 
izes 2 D. of the 3.50 D. of myopia in the meridian at 125°, 
thus leaving 1.50 D. of myopia in this meridian still to be 
corrected, which requires — 1.50 D. cyl., 35°. But instead 
of giving the cross-cylindrical glass, I chose the sphero-cylin- 
drical -(-2 D. — 3.50 D. cyl., 35°. First, because it was 




145 




R. E. 



L. E. 



Fig. 69. 



cheaper ; second, because the astigmatism was not very large 
in amount, and the sphero-cylindrical glass in the right eye 
was made equal in weight with the opposite glass in the left eye. 
The two glasses, the cross-cjdindrical and the sphero-cylin- 
drical, are exactly the same in effect, except that the cross- 
cylinders give a little wider field of vision. Thus the -f- 2 D. 
spherical glass combined with the — 3.50 D. cyl., 35°, acts with 
full force along the axis of the minus cylinder, that is, in the 
meridian at 35°, therefore acting as a -h 2 D. cyl., axis 125° ; 
and, at the same time, it neutralizes 2 D. of the 3.50 D. cyl. in 



ILLUSTRATIVE CASES 161 

the meridian at 125°, leaving but 1.50 D. of this cylindrical 
glass to act in this (125°) meridian, thus acting exactly the 
same as a — 1.50 D. cyl., 35°. 

I go particularly into these changes of glasses rendered 
necessary by the presence of presbyopia in myopic astigmatism, 
and have, in the chapter on simple myopic astigmatism, made 
diagrams of the changes of focus in the eye caused by pres- 
byopia in such cases. For beginners especially, I think it 
most desirable to make diagrams of the foci of the two chief 
meridians of the eye, as indicated by the examination made and 
the glasses accepted, just as I have done in most of the cases so 
far reported ; then to note the effect and changes of focus that 
1 D. of presbyopia causes in each meridian separately ; or v^hat 
change 2 or 3 D., or whatever amount of presbyopia present 
would cause ; make diagrams of these latter foci, when no con- 
fusion as to the proper reading glass can arise. For instance, 
in the case just reported, right eye, for distant vision, the 
meridian at 35° is emmetropic, and focusses rays of light on 
the retina, while the meridian at 125° is mj^opic by 3.50 D., 
and focusses rays of light in front of the retina (see Fig. 69). 
Now, a presbyopia of 1 D. would cause the focus in each 
meridian to recede to the extent of 1 D. (as measured by 
glasses) for the reading distance, that is, the emmetropic merid- 
ian at 35° would focus back of the retina 1 D., and the my- 
opic meridian at 125° would focus but 2.50 D.^ in front of 
the retina, instead of 3.50 as for the distance. With 1 D. of 
presbyopia present in such a case as this, the correct reading- 
glass would be, in cross-cylinders : + 1 D. cyl., 125° — 2.50 D. 
cyl., 35° ; or, in sphero-cylindrical, + 1 D. — 3.50 D. cyl., 35°. 

1 In speaking of the meridians focussing- so many diopters in front or back of 
the retina, I am not unmhidful of the fact that we usually speak of the focus as 
being at a certain linear distance in front or back of the retina. However, 
as this linear distance is fairly well expressed, relatively so at least, by the power 
of the glass it takes to correct the error, 1 have used the power of the glass as 
expressing these distances. 



162 THE REFRACTION OF THE EYE 

For 2 D. of presbyopia, which is actually present in this 
case, we have already shown what the correct reading glasses 
would be (see test). For 3 D. of presbyopia, the focus for 
the meridian at 35° for reading would be 3 D. back of the ret- 
ina, and for the meridian at 125°, .50 D. in front of the retina. 
For correction, in cross-cylinders, it would take : + 3 D. cyl., 
125° — .50 D. cyl., 35° ; or, in sphero-cylindrical, -f 3 D. 
— 3.50 D. cyl., 35° (or, if we chose to give a minus sphere 
and a plus cylinder, —.50 D. + 3.50 D. cyl., 125°, which would 
be a lighter glass in this instance). For 4 D. of presbyopia, 
the myopic astigmatism would be entirely neutralized, and the 
focus for reading in the meridian at 35° would be 4 D. back of 
the retina, while the focus for the meridian at 125° would also 
be back of the retina, to the extent of .50 D. In effect, there- 
fore, for the reading distance, the patient is compound hyper- 
metropic astigmatic, and would require for a reading glass, 
right eye, + .50 D. + 3.50 D. cyl., 125°. 

In the present case, the left eye has 4 D. jof myopia, in 
addition to the astigmatism of 3.50 D. Of course, it would 
take 4 D. of presbyopia to neutralize this myopia, before the 
astigmatism would be affected, and, after which, exactly the 
same change in glasses for the left eye would be required as 
has taken place in the right eye. 

I am aAvare of the fact that this method of making diagrams 
of the foci of the chief meridians of the eye for the distance, 
then noting the change in focus brought about in each meridian 
for a certain amount of presbyopia, takes more time than the 
one of simple algebraic equations ; but it has the great advan- 
tage of fixing the examiner's attention on the real condition 
and foci of the different meridians of the eye, thus making it 
a concrete case. With algebraic equations to ascertain the cor- 
rect reading glass, it becomes a matter of abstract fact to a 
certain extent, and the observer, if he be a beginner, does not 
keep in mind the real condition of the eye, but fits the glasses 



ANTIMETROPIA 163 

empirically. For example, take the left eye in the present case, 
where the distance glass accepted is — 4 D. — 3.50 D. cyl., 
145°. At fifty years of age, with 2 D. of presbyopia present, 
the patient requires + 2 D. added to the distance glasses to get 
the correct reading glass. Algebraically it is : — 



-4D. -3.50D. cyl., 145°. 

+ 2D. 

-2D.- 3.50 D. cyl., 145°. 

For 4 D. of presbyopia it would be : — 

-4 D. -3.50 D. cyl., 145°. 

4-4D. 

• - 3.50 D. cyl., 145°. 



(I) 



(11) 



Now this is perfectly correct in each instance, but if the 
examiner is not familiar with optics, unless he makes a diagram 
of the change of focus brought about by the presbyopia for the 
reading point, he will not likely have a clear idea of the real 
condition of the eye. 

Antimetropia 

The word anisometropia is often used for, and intended to 
convey the meaning of, the word antimetroina. Antimetropia 
means opposite state of refraction of the two eyes, myopic in 
nature in one eye and hypermetropic in the other, and is from 
the three Greek words, avri^ opposite, ixerpov^ measure, and 
^'oyln<;^ vision ; while anisometropia is from avtcro^, unequal, 
jjLeTpov^ measure, and "oyjrt^^ vision, and means an loiecpial state 
of refraction of the two eyes ; that is, both eyes being either 
hypermetropic or myopic, one of the eyes is more hj'perme- 
tropic or myopic than the other. Therefore, there is a distinct 
difference in the meaning of the two words, and they also indi- 
cate quite different conditions in the eyes, and they should not, 
on that account, be confounded one with the other, as is so often 



164 THE REFRACTION OF THE EYE 

done. Anisometropia is quite common, while antimetropia is 
rare. 

Antimetropia is one of the most annoying errors of refrac- 
tion, outside of conical cornea and irregular astigmatism, which 
are really pathological conditions rather than refractive, that 
we have to deal with. In some cases, in fact, one eye has to be 
fitted by itself, while the other has to be left alone, as the two 
cannot be made to work together. And this happens oftenest 
where the error is of large amount in one eye, associated with 
amblyopia ; while the other eye has only a small or moderate 
error of refraction and with no amblyoj)ia. 

There are three or four reasons why antimetropes have 
trouble in using the two eyes together for binocular single 
vision. First, in such cases, it is difficult to fuse the poor 
image of the amblyopic eye with the clear image of the good 
eye so as to make but a single image in the brain center ; 
second, for objects near at hand, it is difficult to converge the 
myopic or long eyeball to the same extent as the hypermetropic 
or short eyeball, again rendering single binocular vision diffi- 
cult ; thirds if the myopia is of high degree and fully cor- 
rected, the patient will have difficulty i;i accommodating for 
near objects with that eye as compared with the hypermetropic 
eye, for its ciliary muscle is much weaker than that of the 
hypermetropic eye ; fourth, the images of objects are different 
in size in the two eyes. 

Some antimetropes are so fortunate as to be able to use the' 
hypermetropic eye for distant vision and the myopic eye for 
near vision, thus using the eyes alternately and singly, and not 
together. In this way they are able to go without glasses, and 
make this, what to many is a veritable burden, an advantage 
in their favor over ordinary mortals. But they are the rare 
exceptions. 

In many of these cases, where one eye is used constantly -to 
the exclusion of the other, the unused eye drops out of the line 



ANTIMETROPIA 165 

of vision and usually squints outward. However, I have 
known the amblyopic eye, which was highly myopic, to squint 
inward. 

My plan of procedure in antimetropia is to fit the eyes 
separately, just as in other cases, and whatever glasses are 
accepted, have the patient wear them faithfully for a period of 
one month at least. If they do not give relief, I then usually 
leave the correction on the better eye, and place a plain glass 
in front of the bad eye. Each case, to a certain extent, is a 
law unto itself, however, and must be dealt with accordingly. 
A few concrete cases will give some idea how these patients 
are to be managed. 

Case LXV. Antimetropia with hlejjharitis marginalis ; 
Simple liypermetropic astigmatism m one eye and simple myopic 
astigmatism in the other ^ ivith the rule in each eye. — November 
19, 1895, Nellie R., aged twenty-two years, in good general 
health, consulted me on account of great pain in the eyes, 
accompanied with severe headaches. She wanted very much 
to be relieved of redness of the eyelids, which remained irri- 
tated and more or less inflamed all the time. 

Ophthalmometer. — Astigmatism with the rule, 1 D., axis 
90°+ or 180°- in each eye. 

Test cards and trial lenses. — The vertical lines on the 
clock-dial were seen plainest with the right eye, and the hori- 
zontal lines were seen best with the left eye. 

R. Y. = 1^ : I^W. - .50 D. cyl., 180°. 
L. Y. = |o 4- : i| W. + .50 D. cyl., 90°. 

Reads Jaeger No. 1 from 6 to 17 inches. 

Ophthalmoscope. —M. .75 D. at 90° and Em. at 180° right 
eye ; Em. at 90° and H. .75 D. at 180° left eye. 

A saturated solution of boracic acid was ordered as a wash 
for the eyelids, to be used twice a day : and the yellow oxide 



166 



THE REFEACTION OF THE EYE 



of mercury ointment (gr. viii to Si vaseline) was ordered to be 
rubbed on the eyelids at bedtime. 

After a week, in which time the lids improved but little, 
a second test was made for glasses. The patient accepted 
exactly the same glasses as at the first test. Ordered for con- 
stant wear: — .50D. cyl., 180° right eye, and + .50 D. cyl., 
90° left eye. Within a month the eyelids were well of their 
inflammation, the pains in the eyes and the headaches gone, 
and the patient happy. She has continued to wear the glasses 



180 




180 




R. E. 



L. E. 



Fig. 70. 



ever since with great satisfaction. With large errors of refrac- 
tion of this nature, however, glasses do not usually give so 
good a result. 

Attention may be called to the reading of the ophthal- 
mometer in this case. The instrument read exactly the same 
amount and the same axis of astigmatism in each eye. Fol- 
lowing my routine practice of beginning the test with weak 
plus glasses (cylinders where there is astigmatism), I found, 
they would not be accepted by the right eye. I then tried a 



ANTIMETROPIA 167 

weak minus cylinder, axis 180°, as indicated by the instrument, 
and it was accepted, a — .50 D. cyl., 180°, giving the best 
vision. Although I found simple myopic astigmatism in the 
right, I again followed my routine method of trying plus 
glasses first on the left eye, and found that they were accepted, 
a +.50 D. cyl., 90°, giving the best vision. Had minus cylin- 
drical glasses been tried first on the left eye, I am convinced 
she would have accepted them, as she had on previous tests, 
and from which glass she got no relief from her asthenopia or 
red eyelids. 

It must always be remembered that the ophthalmometer 
does not reveal to us the nature of the error of refraction, 
— that is, if hypermetropic or myopic, — but simply the 
axis and the amount of the corneal astigmatism. But, with 
this much known, by following the routine method already 
given in detail in previous pages of this book, nearly 
every case can be fitted correctly and without the use of a 
mydriatic. 

Case LXVI. Antimetropia ; Amblyopia to some extent; Sim- 
ple hypermetropic astigmatism in one eye^ and simple myojpic astig- 
matism in the other^ with the rule in each. — February 13, 1897, 
M. F., aged eighteen, in good health, consulted me for glasses 
on account of poor vision, and because of pain in the eyes and 
headaches when she persists in using the eyes. 

Ophthalmometer. — Astigmatism with the rule, 2 D., axis 
75° + or 165° - right eye ; 2D. with the rule, axis 105° + or 
15° - left eye. 

Test cards and trial lenses. — 

R. V. = f ^ - : 1^ W. + 1.75 D. cyl., 75°. 
L. V. = f^ - : 20. W.- 1.75 D. cyl., 15°. 

Reads Jaeger No. 1 from 6 to 12 inches, and has single 
binocular vision. 



168 



THE REFRACTIOX OF THE EYE 



Em. at 75° and H. 2 D. at 165° right 



OphtJialmoscope. 
eye ; M. 2 D. at 105° and Em. at 15° left eye. 

A second and a third test resulted in the patient accepting 
the same glasses as at the first test. Ordered + 1.75 D. cyl., 



165 




R. E. 



L. E. 



Fig. 71. 



75° right eye, — 1.75 D. cyl., 15° left eye. These glasses have 
been worn for more than a year, with relief from her asthenopic 
vision. 

Case LXVII. Antimetropia ; Asthenopia; Simple hyperme- 
tropic astigmatism in one eye^ and compound myopic astigmatism 
in the other^ ivith the ride in each. — August 11, 1896, James 
McG., aged thirty years, came to the clinic of Drs. Lewis and 
Van Fleet, at the Manhattan Eye and Ear Hospital, because 
of pain in his eyes and on account of severe headaches. His 
eyes have always given him trouble, both for far and near 
vision. The pains in the head are confined to the frontal 
region chiefly. 



ANTIMETROPIA 



169 



Ophthalmometer. — Astigmatism with the rule, 1 D., axis 
90° + or 180° - in each eye. 
Test cards and trial lenses. — 

R. Y. =|§-:l|W.+.50 D. cyl.,90°. 

L. V. = If - : ff W. - 1 D. - .50 D. cyl., 180°. 

Reads Jaeger No. 1, 5 to 12 inches. 

Ophthalmoscope. —^m. at 90° and H. .50 D. at 180° right 
eye ; M. 1.50 D. at 90° and M. 1 D. at 180° left eye. 




180 



R. E. 




Fig. 72. 



Second test : the patient accepted exactly the same glass 
as at the first test, and it was ordered. It took two weeks 
persistent wearing before the patient got accustomed to the 
glasses ; but at the end of that time his eyes were entirely 
comfortable and his headaches relieved. After the first month 
the patient was lost sight of. 

Case LXVIIT. Antimetropia ; Compound hiipcrmctropic 
astigmatism in one eye and compound myopic asti(/niatis)n in the 
other, against the rule in the inyopic eye and with the rule in the 



170 THE REFRACTION OF THE EYE 

hypermetropic eye; Marked asthenopia relieved ivith glasses. — 
November 19, 1895, Harriet W., aged twelve years, in good 
health, consults me on account of blurred vision and headaches, 
especially annoying in the afternoon at school. She has worn 
glasses, but without relief. 

Ophthalmometer. — Negative right eye ; astigmatism with 
the rule, .75 D., axis 90° + 180° - left eye. 

Test cards and trial lenses. — 

R. V. = 1^^ : not improved. 
L. V. = f^:||W.+ l.D. 

Reads Jaeger No. 1 from 5 to 12 inches. Signs of spasm 
of accommodation are j)i^esent. 

Ophthalmoscope. —M. 1 D. right eye; H. .50 D. at 90° 
and H. 1 D. at 180° left eye. 

On account of a conjunctivitis, an astringent wash was 
ordered for the eyes, and the patient directed to come again in 
three days. 

Second test : the ophthalmometer read the same as at the 
first test. 

Test cards and trial lerises. — 

^' ^' = U'- U ^^' - -5^ ^' - -50 1^- cyi., 105°. 

L. V. = 1^ : ff W. + .50 D. + .50 D. cyl., 90°. 

Reads Jaeger No. 1, 5 to 15 inches. 

Ophthalmoscope. —U. .50 D. at 105° and M. 1 D. at 15° 
right eye; H. .50 D. at 90° and H. ID. at 180° left eye. 

On a third test the patient accepted the same glasses as 
on the second test, and they were accordingly ordered. They 
have been worn for more than two years with relief from all 
asthenopic symptoms. 

In this case the ophthalmometer showed no corneal astig- 
matism in the right eye, and, as usual in such cases, the patient 
accepted a cylindrical glass against the rule 



ANTIMETROPIA 



171 



On the first test there was some spasm of accommodation, 
due to irritation of the eye from a mild conjunctivitis. After 
a few days' treatment this disappeared, the second and third 
tests agreed, and the glasses were ordered. 




180 




R. E. 



L. E. 



Fig. 73. 



Case LXIX. Antimetropia ; Mixed astigmatism rights and 
'Compound myopic astigmatism left^ eye ; Head carried to the right 
side; Asthefioj^ia ; Relief with glasses. — November 22, 1897, 
Mary McG., aged twenty-three years, in good health, consulted 
me on account of headaches and pains in the eyes. She has 
a tendency to hold her head to the right, especially for close 
work. Her left eye has troubled her a great deal for the last 
eighteen months, and sometimes sharp pains shoot through it. 
The left eye is very sensitive to bright light and heat. 

Ophthalmometer. — Astigmatism with the rule, 2.50 D., axis 
45° + or 135°- right eye ; 2.50 D., axis 60° + or 150°- left eye. 

Test cards and trial lenses. — 



2 00 . 10 - W. + 2 D. cyl., 45° - .50 D. cyl., 135°. 



R. V. - -2JL . 2 

^- ^' = 2^0 • To^ W. - 10 D. - 2. D. cyl., 150°. 



172 



THE REFRACTIOX OF THE EYE 



Reads Jaeger No. 1, 6 to 10 inches, with the right eye. 
Single binocular vision is not present. 

Ophthalmoscope. — YL. I'D, at 135° and M. ID. at 45^ 
right eye; M. 13 D. at 60° and 11 D. at 150° left eye. 




R. E. 



L. E. 



Fig. 74. 



Second test : two days later the ophthalmometer gave the 
same reading. 

Test cayxJs and trial lenses. — 



R V = -2JL 

±v. V . 2 

L V — -2- 

^' ^ ~~ 2 00 



1^ + W. + 1 D. cyl., 45° -ID. cyl., 135°. 



__2_o_ W — 1 D 

100 ^^ ' ^^ ^' 



2D. cyl., 150°. 



A third test coincided with the second, and the glasses were' 
ordered. The patient has been greatly benefited, the pain in 
the eyes and head disappeared after about two weeks' time ; 
and after the first month she has been able to hold her head 
straight. She wore these glasses continuously till November 
22, 1898, just one year, when she returned, complaining of 
pain in the right eye. On examination I found that the 
astigmatism had increased one-quarter of a diopter, and had 



ANTIMETROPIA 17g 

changed axis to the extent of 10°, that is, from 45° to 35°, 
and from 135° to 125°, respectively. The patient accepted 
+ 1 D. cyl., 35° - 1.25 D. cyl., 125° right eye. The left eye 
had not changed, and the old glass was left. The new glass 
has relieved the pain in the right eye, and the patient is again , 
comfortable, and carries her head perfectly straight. 

Case LXX. Antimetropia ; Simple Jiypermetropia right eye; 
Simple myopia of large a7noimt ivitli convergent strabismus left eye ; 
Correction of strabismus with glasses without operation. — Marcli 
10, 1892, Emma S., aged eighteen years, in poor health, con- 
sulted me on account of a trachoma and convergent strabismus 
of the left eye. She is anaemic and much run down, has but 
poor appetite, and is now under treatment for nervous dyspep- 
sia. There is considerable inflammation in the lids, with some 
discharge. 

After five months' treatment of the lids with the usual local 
applications, and with general tonics, the patient's condition 
was greatly improved in every way. At the end of this time 
I gave the first test for glasses as follows : — 

Ophthalmometer. — Astigmatism with the rule, .50 D., axis 
90° + or 180° - each eye. 

Test cards and trial lenses. — 

T. V — -^- • -2JL W _ 1 B D 

-^* ^'"200*200 ^^ ' ±u J^. 

Reads Jaeger No. 1, 6 to 15 inches, with the right e3^e. 

Ophthalmoscope. — H. 1.50 D. right eye; M. 17 D. left eye, 
with posterior staphyloma, choroiditis, and floating bodies in 
the vitreous. 

Second test: this corresponded with the first, and + ID. 
right eye and — 10 D. left eye were ordered, to be worn con- 
stantly. After about six weeks' time the left or myopic eye 
no longer squinted, which was most gratifying both to the 
patient and myself. 



174 THE REFRACTIOX OF THE EYE 

The patient has been under my observation for six years^ 
and the eyes remain perfectly straight, although she has not 
single binocular vision. 

I account for the correction of the convergent strabismus in 
the myopic eye by means of glasses in this case in exactly the 
way as the ordinary convergent squint of hypermetropia is 
corrected b}^ glasses, as follows : the patient, being in poor 
health and having 1 D. of manifest h3^permetropia in the right 
eye, converged the left amblyopic eye unduly inward in order 
to assist the accommodation in the right eye, that is, squinted 
the left eye inward. When the manifest hypermetropia in the 
right eye was corrected with a plus glass, there was no need 
of extra accommodative power in that eye, so the patient no 
longer squinted or converged the left eye too far inward, but 
relaxed this effort, and the left eye became straight ; that is, 
parallel with the right. 



CHAPTER VII 

MIXED ASTIGMATISM — ILLUSTRATIVE CASES 

Perhaps mixed astigmatism is the most troublesome error 
of refraction which we are called upon to correct, and many 
oculists never attempt to correct a case of mixed astigmatism 
without the use of a mydriatic. To beginners, such cases are 
puzzling, and the examiner is often led to make prolonged and 
unnecessary tests. As for myself, I never think of using a 
mydriatic in mixed astigmatism, unless there is a tendency to, 
or an actual spasm of, accommodation, any more than I do in 
cases of simpler errors of refraction. 

The ophthalmometer scores one of its greatest triumphs in 
just these cases, and does away with the necessity and bother 
of using a mydriatic. I grant, however, retinoscopy is a 
valuable method of testing where a mydriatic is used. But 
the use of a mydriatic is just what we wish to avoid if pos- 
sible. With the use of the ophthalmometer and a routine 
method of testing the cases, we are able, in the great majority 
of cases, to avoid the use of a mydriatic altogether. On the 
other hand, to make retinoscopy effective in these cases, or in 
any other for that matter, a mydriatic must be used. 

I begin my test in these cases in exactly the same manner 
as in all others, that is, I ascertain with the ophthalmometer 
the amount and axis of the corneal astigmatism. Sa}', for 
example, the instrument reads astigmatism with the rule, 
2.50 D., axis 90° + or 180° -. The first glass that I try is 
a + .25 D. cyl., 90°. If this improves vision, I gradually 
increase its strength (+ .25 D. at a time) until the plus cylin- 

175 



176 THE REFRACTION OF THE EYE 

clrical glasses cease to improve the vision. By way of illus- 
tration in this supposed case, say the patient accepted + 1 D. 
cyl., 90°, and the vision was improved from y^JL to |-Q-, but that 
when a +1.25 D. cyl., 90°, was tried it made the vision worse. 
Now, since the instrument showed the patient to have 2.50 D. 
of astigmatism, and as he accepted only 1 D. of that amount 
in plus glasses, I would immediately suspect mixed astigma- 
tism, especially if a weak plus spherical glass in addition to 
the cylinder did not further improve vision. I would then 
try a — .25 D. cyl., 180°, that is at right angles to the plus 
cylinder. If this improved vision, it should be increased in 
strength, a quarter diopter at a time, until the vision ceased 
to be improved thereby, being careful to stop with the weakest 
minus glass that gave the best vision. We will say —ID. 
cyl., 180°, in this instance, and that the vision was further im- 
proved over that obtained by the plus cylinder alone, |-§- to |-§-, 
with the two cylinders combined. This would indicate a case 
of mixed astigmatism, equally divided as to hypermetropia 
and myopia, or 1 D. of each, and 2 D. of astigmatism all 
told. Deducting .50 D. from the reading of the ophthal- 
mometer (which was 2.50 D.), since the astigmatism was^ 
"with the rule," it leaves just 2 D, of astigmatism to be 
corrected. Of course, a second test should be given in all 
cases of mixed astigmatism, and if the glasses on the sec- 
ond test agree with the first test, I do not hesitate to give 
them. Sometimes it is necessary to give a third test. I may 
say it is exceptional for me not to be able to fit such cases 
without the use of a mydriatic. 

Knowing the amount of the astigmatism from the reading 
of the instrument, we can readily see how close the astigma- 
tism, as indicated by the glasses accepted, corresponds with 
it. In this way we are put on guard against giving too strong 
minus cylinders in such cases, as is often done, especially 
where the test is improperly begun with minus glasses. 



I 



MIXED ASTIGMATISM 177 

Since it is of great importance in ordinary cases to begin the 
test for glasses with plus glasses, how much more important is 
it to begin the test with plus glasses in these cases of mixed 
astigmatism ? And we must do so, unless we wish to give too 
strong minus cylinders, or use a mydriatic, neither of which 
alternatives is necessary. In fact, I have seen not a few cases 
of mixed astigmatism fitted with minus cylindrical glasses. 
So easy is it to fall into this error, that I venture to present 
a diagram of such a case, and in this way demonstrate how 
such mistakes are made. I thus hope to keep beginners from 
blundering. 

As an example, we will take the case just cited above, 
where the ophthalmometer read astigmatism Avith the rule, 
2.50 D., axis 90° + or 180° — , and the patient accepted 
+ 1 D. cyl., 90° -ID. cyl., 180°. 

Now, if instead of beginning the test with weak plus cylin- 
drical glasses, as we did, say we began with minus cylinders, 
and gradually increased them in strength. In place of stop- 
ping with — 1 D. cyl., 180°, the exact correction of the 
myopic astigmatism, the patient would most likely have ac- 
cepted — 2D. cyl., 180°, the total amount of the astigmatism 
present. In this way the mixed astigmatism is converted into 
a simple hypermetropia of 1 D. 

A glance at Fig. 75 will show how this is brought about. 
The —2D. cyl., 180°, not only corrects the myopia of ID. in 
the vertical meridian, but diverges the rays in that meridian 
1 D. back of the retina. Now, since the eye is already hyper- 
metropic 1 D. in the horizontal meridian, Ave CAadently have 
in effect 1 D. of simple lij^permetropia present; which induced 
hypermetropia, by the Avay, the patient can and often will cor- 
rect by the use of the ciliary muscle, since he uoav can use it 
in its entire circumference. Not onl}^ can the patient do this, 
but, if his accommodative power is strong, he sometimes does 
it with comfort. Hence the relief for a time from asthenopia 



178 



THE REFRACTION OF THE EYE 



sometimes in mixed astigmatism, even with simple minus 
cylindrical glasses. 

Incidentally, I might say, a case similar in effect to this is 
where a patient with simple hypermetropic astigmatism accepts 
a simple myopic cylindrical glass. For example, say a patient 
should wear a + 1 D. cyl., 90°, to correct a simple hyperme- 
tropic astigmatism of that amount. Now instead of this he 
will sometimes accept — ID. cyl., 180°, especially so if minus 





180 



180 




Fig. 75. — (A) Before correction. (B) After correction with —2D. cyl., axis 180°^ 
the mixed astigmatism is converted into a simple hypermetropia of 1 D. 



cylindrical glasses are begun with. The — ID. cyl., 180°, 
converts the patient's simple hypermetropic astigmatism into 
a simple hypermetropia of 1 D. (see Fig. 76). 

The patient by means of his accommodative power can 
correct this simple hypermetropia (as produced by the minus 
cylinder) with comfort at times, because he can use the whole 
of the ciliary muscle regularly ; while he could not correct the 
simple hypermetropic astigmatism without discomfort, since, 
in that case, it must contract irregularly to act on the horizon- 
tal meridian of the lens without at the same time acting on the 



MIXED ASTIGMATISM 



17^ 



vertical meridian, which is emmetropic and should be let alone. 
Such is the simple explanation of these cases. No stronger- 
plea could be urged for the beginning of all tests with plus 
glasses, I am sure. 

To recapitulate : most cases of mixed astigmatism can be 
correctly fitted with glasses without the use of a mydriatic,, 
provided that first, the amount and axis of the corneal astig- 
matism be ascertained ; next, that the test for glasses be begun 




Fig. 76.— (A) Before correction. (B) After correction with —ID cyl., 180°, hy 
which the simple hypermetropic astigmatism is converted into a simple hyper- 
metropia of 1 D. 

with weak plus glasses and their strength gradually increased i 
and finally minus glasses tried. 

The chief indication for a mydriatic in such cases, as in all 
other cases of refractive error, is a spasm of accommodation. 
The means of detecting spasm of accommodation have already 
been pointed out elsewhere, so we need not consider them 



Case LXXIo 3Iixed astigmatism of large amount and with 
the rule m each eye; Asthenopia; Relief ivitli glasses. — April -1. 



180 THE refractio:n^ of the eye 

1893, Miss S. A., aged twenty-two years, in good general 
health, has had trouble with her eyes for the last six years. 
She now complains of having to hold the print too close to her 
eyes when she reads, also of headache and pain in the eyes 
after reading or sewing. She has three brothers and one sister, 
none of whom are troubled with their eyes. 

Ophtliahnometer. — Astigmatism with the rule, 4 D., axis 
T5° + or 165° — right eye ; 5 D., axis 95° + or 5° — left eye. 

Test cards and trial 



R. Y. = 2^0 : 1^ W. + 1.75 D. cyl., 75° - 1.75 D. cyl., 165°. 
L- ^- = 2W • I* W. + 3.25 D. cyl., 95° - 1 D. cyl., 5°. 

Reads Jaeger No. 1 from 8 to 15 inches. 

Ophthalmoscoj^e. —M. 2D. at 75° and H. 2D. at 165° right 
eye ; M. 1 D. at 95° and H. 4 D. at 5° left eye. 

Second test : three days later the ophthalmometer gave ex- 
actly the same reading as at the first test. 
Test cards and trial 



I^- ^- = 2% • 1* "^^^ + 2 D. cyl., 75° - 1.50 D. cyL, 165°. 
L. V. = 2VV : 1^ W. + 3.50 D. cyl., 95° - .75 D. cyl., 5°. 

The ophthalmoscope agreed practically with the first exami- 
nation. I ordered the glasses that were accepted on the second 
test in sphero-cylinders, to wit: — 1.50 D. -f 3.50 D. cyl., 75° 
right; and - .75 D. +4.25 D. cyl., 95° left. These glasses 
have been worn with great satisfaction from the first, and have 
not been changed. 

It will be noticed that I ordered a sphero-cylindrical glass 
instead of cross-cylinders. In this instance I gave sphero- 
cylinders, because by actual trial in the trial frames the sphero- 
cylinders were more comfortable to the patient and gave equally 
as good vision. It will be seen also that I gave a minus sphere 
with a plus cylinder. There was a reason for this. In this 
case the minus spheres combined with plus cylinders is a 



MIXED ASTIGMATISM 



181 



much lighter glass than had we given plus spheres with minus 
cylinders. For example, take the glass for the left eye : 
— .75 D. + 4.25 D. cyl., 95°, is a much lighter glass than 
+ 3.50D. cyl., 95°- 4.25 D. cyl., 5°, though the glasses are 
identical in effect with each other, as they are, indeed, with 
the cross-cylinders, + 3.50 D. cyl., 95° — .75 D. cyl., 5°, from 
which they are transposed. 

Where we have mixed astigmatism in one eye only, when 
we convert a cross-cylinder into a sphero-cylinder we have to 




R. E. 



L. E. 



Fig. 77. 



pay some regard to the axis of the cylinder in the other eye, 
if astigmatism of a simple or compound nature is present — a 
point which will be illustrated by cases to follow. 

In small and moderate degrees of mixed astigmatism, instead 
of giving cross-cylinders, a sphero-cylinder is most often to be 
preferred, for the reason that it is a cheaper glass than the 
cross-cylinders. But in high degrees of mixed astigmatism 
cross-cylinders are to be preferred to sphero-cylinders, because 
they give a broader field of vision. The method of converting 



182 THE REFRACTIOX OF THE EYE 

cross-cylinders into sphero-cylinders is a very simple one ; if you 
please, the simplest of algebraic equations. For the benefit of 
any one who may not understand algebraic equations, I may say 
that I shall use the simplest terms, so that even they may 
understand the method. I will give a concrete case in order 
to illustrate the more plainly. Take the last case cited, right 
eye, where the patient accepts a + 2 D. cyl., 75° — 1.50 D. cyl., 
165°. To convert this into a sphero-cylinder (plus sphere witlx 
a minus cylinder) give a + 2 D. sphere in place of the 2 D. cyl.,, 
then transpose 2 D. to the opposite side of the equation, chang- 
ing the sign with the transposition, and add this amount (2 D.) 
to the - 1.50 D. cyl., which would give - 3.50 D. cyl., 165°,. 
the axis of the minus cylinder remaining unchanged. The 
transposed glass is written thus : + 2 D. — 3.50 D. cyl., 165°. 

To convert this same cross-cylinder into a sphero-cylinder 
(minus sphere with a plus cylinder) give a — 1.50 D. sphere 
in place of the — 1.50 D. cyl., then transpose — 1.50 D. to the 
opposite side of the equation, changing the sign in the transpo- 
sition, and add this amount (1.50 D.) to the + 2 D. cyl., which 
would give +3.50D. cyl., 75°, the axis of the plus cylinder 
remaining unchanged. The transposed glass is written thus ; 
-1.50D. 4-3.50D. cyL, 75°. 

In other words, if we wish to convert a cross-cylinder into a 
sphero-cylinder (a plus sphere with a minus cylinder), all that 
it is necessary to do is to give in place of the plus cylinder a 
plus sphere of equal strength, then add this amount to the 
strength of the minus cylinder, leaving its axis unchanged. 
If we wish to convert it into a sphero-cylinder (minus sphere 
with a plus cjdinder), all that is necessary to do is to give in 
place of the minus cylinder a minus sphere of equal strength, 
and add this same amount to the plus cylinder, leaving its axis 
unchanged. 

This explanation I am sure is plain enough, even to a man 
who never heard of algebra. 



TRANSPOSITION OF GLASSES 183 

A glance at Fig. 77 will show how each of the three 
glasses, — 

(1) + 2 D. cyl., 75° - 1.50 D. cyl., 165°; 

(2) -I-2D. - 3.50D. cyl., 165°; 

(3) - 1.50 D. -f- 3.50 D. cyl., 75°; 

which are the cross-cylinder and the sphero-cylinders into 
which it is capable of being converted, can correct the mixed 
astigmatism in the right eye. 

With glass No. 1, the cross-cylinder, the + 2 D. cyl., 75°, 
corrects the hypermetropia at 165° (cylinders always acting at 
right angles to their axes), while the — 1.50 D. cyl., 165°, cor- 
rects the myopia at 75°; thus the eye is rendered emmetropic, 
or corrected. With glass No. 2, the + 2 D. corrects the 
hypermetropia at 165° ; but, since it acts in its whole cir- 
cumference, it makes the myopia worse to that extent (2D.) 
in the meridian at 75°, consequently that amount has to be 
added to the - 1.50 D. cyl., making it - 3.50 D. cyh, 165°. 
With glass No. 3, the — 1.50 D. corrects the myopia in 
the meridian at 75°; but here again, since it acts in its entire 
circumference, it makes the hypermetropia worse to that extent 
(1.50 D.) in the meridian at 165°; therefore that amount has 
to be added to the + 2 D. cyl., making it -f 3.50 D. cyl., 75°. 

As a rule, when converting cross-cylinders into sphero- 
cylinders, the weaker cylinder should be converted into the 
sphere and the same amount added to the stronger cylinder ; 
because such a combination makes a lighter glass than where 
the stronger cylinder is converted into a sphere and the Aveaker 
cylinder added to it (see example, p. 181, this chapter). How- 
ever, in making a choice, some regard must be paid to the 
opposite eye, if astigmatism is present in that eye, and espe- 
cially if not of the mixed variety. Several concrete cases will 
serve to illustrate these points better than mere statements. 



184 THE REFRACTION" OF THE EYE 

Case LXXII. Mixed astigmatism of large amount^ with 
the rule and at off axes; Marked asthenopia^ severe headaches^ 
dizziness ; Relief ivith glasses. — February 27, 1897, Mrs. F. 
li. P., aged twenty-six years, in good health, has worn glasses 
at ^imes since a child, but none of the glasses were satis- 
facb^ry. When she reads, her eyes and head ache, and if she 
persists in reading for any considerable length of time, she 
becomes dizzy. 

Ophthalmometer. — Astigmatism with the rule, 5 D., axis 
105° + or 15° - right eye; 6 D., axis 75° + or 165° - left 
eye. 

Test cards a7id trial lenses. — 

'^' ^' = 2¥o • y^ ^^' + 1 D- cyl., 105° - 3.50 D. cyl., 15°. 
L- V. = 2V0 : f^ W. + 1 D. cyl., 75° - 4.50 D. cyl., 165°. 

Reads Jaeger No. 1, 5J- to 12 inches. 

Ophthalmoscope. — M. 4 D. at 105° and H. 1 D. at 15° right 
eye ; M. 5 D. at 75° and H. 1 D. at 165° left eye. 

Second test : four days later the ophthalmometer gave the 
same reading in the right eye, but varied 5° as to the axis in 
the left eye, giving 6 D., axis 70° + or 160° — . 

Test cards and trial lenses. — 

^' ^' = 2¥o • 1^ ^^- + 1-25 D. cyl., 105° - 3.25 D. cyl., 15°. 
L- V. = 2V0 • U ^^' +1 ^' cyl., 70° - 4.50 D. cyl., 160°. 

Reads Jaeger No. 1, 5^ to 12 inches. 

This last glass was ordered as a sphero-cylinder (plus sphere 
with a minus cylinder). Usually, in a case with as large amount 
of mixed astigmatism as in this case, we prescribe cross-cylinders, 
because it gives a broader field of vision. But in this instance 
so much of the glass was minus and so little plus that I gave 
sphero-cylinders. Had the hypermetropic and myopic portions 
of the astigmatism been nearly or exactly equal, I should have 



ILLUSTRATIVE CASES 



185 



given cross-cylinders, because they would have given a broader 
field of vision than the sphero-cylinders. 

Again, in the present case, although I converted the cross- 
cylinders into a sphero-cylinder, a plus sphere with a minus 
cylinder, I would not for a moment think to convert them 
into a sphero-cylinder with a minus sphere and a plus cyl- 
inder, because it would have made a very heavy glass, to 
wit: -3.25 D. -f- 4.50 D. cyL, 105° right eye; - 4.50 D. 
+ 5.50 D. cyl., 70° left eye. Although this glass is identically 




Fig. 78. 



the same in effect as the cross-cylinder, and the sphero-C5dinder 
with *a plus sphere and a minus cylinder, it is not to be con- 
sidered at all. 

Sometimes in cases where the cross-cylinders and one of the 
sphero-cylinders into which it can be converted do not differ 
much in weight, as in the cross-cylinder and the sphero-cylin- 
der (the one with a plus sphere and a minus cylinder) in the 
present case, I give a practical test to decide between the fit- 
ness of the two glasses. I first tr}- the cross-cylinders, then 
the sphero-cylinders in the trial frame, and find with which the 



186 THE REFRACTIOX OF THE EYE 

patient sees best and most comfortably, and decide accord- 
ingly. Strange as it may seem, they often see considerably 
better with one glass than the other, although theoretically they 
are supposed to have the same effect. 

Case LXXIII. Mixed astigmatism tvith the rule; No ambly- 
opia; Persistent headaches; Relief ivith glasses. — September 12, 
1894, Annie S., aged forty years, in good health, has suffered 
from headaches all of her life. At times the headaches are 
very severe ; in fact, neuralgic in character, and are intensified 
by any persistent use of the eyes. 

Ophthalmometer. — Astigmatism with the rule, 3.50 D., axis 
100° + or 10° - right eye ; 3.50 D., axis 80° + or 170° - left 
eye. 

Test cards and trial lenses. — 

R. Y. = J^ - : 14 + w. + .T5 D. cyl., 100° -2D. cyl., 10°. 
L, y. = 2^- :2|_|.^Y. _|..75D. cyl., 80° -2D. cyh, 170°. 

With both eyes at once, distant vision = -||-. 

Reads Jaeger Xo. 1 from 8 to 18 inches. 

Ophthalmoscope. — M. 2 D. at 100° and H. 1 D. at 10° right 
eye ; M. 2 D. at 80° and H. 1 D. at 170° left eye. 

The above glasses in the form of sphero-cylinders (+ .75 D. 
- 2.75 D. cyl., 10° right eye ; + .75 D. - 2.75 D. cyL, 170° 
left eye) were prescribed after one test. They gave relief 
almost immediatelj^, and have been worn with comfort* ever 
since. Of late, however, she feels the need of a stronger glass 
for reading, especially at night, and this is to be exjDCcted 
as she is now forty-three years of age, and her presbj'opia 
demands it. 

It will be seen by this case that even cases of mixed astig- 
matism can be fitted correctly, not only without the use of a 
mydriatic, but at one sitting. Of course, the age of the patient, 
she being forty, favored the procedure. In patients under 



ILLUSTRATIVE CASES 



187 



forty years of age, in cases of mixed astigmatism, I always 
give two, and, in most cases three, tests before giving glasses. 

The sphero-cylinder with a plus sphere and a minus cylin- 
der was more desirable than the sphero-cylinder with a minus 




170 



R. E. 




L. E. 



Fig. 79. 



sphere and a plus cylinder, because lighter and with the axes 
of the cylinders horizontally placed, or nearly so, both points 
in its favor. 

Case LXXIY. Mixed astigmatism tvith the ride in one eye ; 
Hypermetropic astigmatism ivith the rule in the other eye; Asthe- 
nopia ; Relief with glasses. — December 19, 1894, Emily R., 
iiged thirty-two years, in perfect health, has always suffered 
with severe headaches and with pain in the eyes. She has been 
wearing glasses for the last nine months, but without much 
relief from her asthenopic symptoms. 

Ophthalmometer. — Astigmatism w^ith the rule, 1 D., axis 
80° + or 170° - right eye ; 4.25 D., axis 105° + or 15° - left 
€ye. 



188 THE EEFRACTIOX OF THE EYE 

Test cards and trial lenses. — The lines in the horizontal me- 
ridian from III to IX are seen plainest in the right eye ; the 
lines from IV to X are seen plainest with the left eye until 
+ 1.25 D. cyl., 105°, is placed before the eye, when all of the 
lines appear alike, but somewhat blurred. And when the entire 
plus cylinder, 2.75 D., is placed in front of the eye, the lines 
from I to VII are seen plainest ; but when — 1.50 D. cyl., 15°, 
is added to the plus cylinder in the frames, all of the lines 
appear alike and plainly. 

^•^•= U''\i-^^'+ .50 D. cyL, 85°. 

L. V. = 2V% : f-^ W. + 2.75 D. cyl., 105° - 1.50 D. cyh 15°.. 

Reads Jaeger Xo. 1 from 7 to 18 inches. 

Ophthalmoscope. — H. 1 D. right eye ; H. 2 D. at 15° and 
M. 2 D. at 105° left eye. 

Second test ; the ophthalmometer read the same exactly as 
at the first test. 

Test cards and trial lenses. — 

R. V. = f § : f I W. + .50 D. cyl., 85°. 

L. V. = 2%: U W. + 2.50 D. cyl., 105° - 1.50 D. cyL, 15°. 

The ophthalmoscope agreed with the first examination- 
Ordered : — 

+ .50 D. cyl., 85° right eye ; 

-1.50 D.+ l D.cyL, 105° left eye. 

I wish to call attention to two points in this case : first, 
the axis of the cylinder in the right eye varied 5° from the 
reading of the ophthalmometer ; second, I converted the cross- 
cylinder in the left eye into a sphero-cylinder, — a minus 
sphere with a plus cylinder, — and for three reasons : (a) to 
make the cylinder correspond to the right eye ; (h) because, 
in this case, it is a lighter glass than the sphero-cylinder with a 
plus sphere and a minus cylinder ; and (c) a cheaper glass. 



ILLUSTRATIVE CASES 



189 



And this brings me to speak, in a general way, in reference 
to such cases as the present one, where there is a mixed astig- 
matism in one eye and simple or compound astigmatism in the 
other. In converting the cross-cylinders into sphero-cylinders, 
some regard must be had that the character (plus or minus) of 
the cylinder in the transposed glass correspond to the cylinder 
in the opposite eye. Because, as a rule, a plus cylinder on one 
eye and a minus cylinder on the other do not work as well 
as when both are positive or negative. This point should be 



105" 




Fig. 80. 



borne in mind, in converting cross-cylinders ; and, unless by so 
doing the weight of the glass is greatly increased, cylinders of 
a like character should be given. Sometimes in such cases it 
is better to give the cross-cylinder in the mixed astigmatic eye. 
especially if the astigmatism is of large amount, rather than 
convert it into a sphero-cylinder, either with plus sphere and 
minus cylinder, or minus sphere and plus cylinder; and, by 
putting the different combinations in front of the eye for a few 
moments, the patient will often make the choice for himself. 



190 THE REFRACTION" OF THE EYE 

Case LXXV. Mixed astigmatism with tJie 7'ide right eye; 
Hypermetropic astigmatism ivith the ride left eye ; Marked asthe- 
nopia ; Spasm of accommodation ; Atropine instilled ; Relief with 
glasses. — February 17, 1894, Pauline J., aged thirty years, is 
in good general health, but has suffered a great deal from head- 
aches and pains in the eyes. It is almost impossible for her to 
use her eyes for close work of any kind, because, of the severe 
headaches and discomfort in the eyes when she attempts such 
work. 

Ophthalmometer. — Astigmatism with the rule, 4.50 D., axis 
90° + or 180° - right eye ; 1.50 D., axis 90° + or 180° - left 
eye. 

Test cards and trial lenses. — Tiie test with the lines on the 
clock-dial were thoroughly unsatisfactory, no definite result 
being obtained by them. 

R. V. = J/o- 1^ W. - 1 D. - 4 D. cyl., 180°. 
L. V. = If: JfW.- ID. cyl., 180°. 

Reads Jaeger No. 1 from 10 to 14 inches. 

With the above glasses the patient would see very well for 
a few moments at a time, then everything would " fade out," 
as she expressed it. In fact, this happened several times 
during the test when the eyes were being tested separately. 
It is unnecessary for me to say that I began the test in each 
eye with my routine method of trying plus glasses first ; but, 
as they were refused, minus glasses were next tried, with the 
above result. 

I suspected spasm of accommodation from the way the eyes 
behaved during the test, the patient being uncertain of the 
glasses, and the letters fading out from time to time. The 
examination with the ophthalmoscope showed the patient to be 
mixed astigmatic in the right eye. Retinoscopy confirmed 
mixed astigmatism in the right eye, but left the diagnosis in 



ILLUSTRATIVE CASES 



191 



the left eye in doubt ; in fact, indicated myopic astigmatism, 
which, under atropine, proved to be hypermetropic astigma- 
tism. 

I might say there were no muscle insufficiencies. 

Atropine solution (4 gr. to Si) was ordered to be instilled, 
one drop in each eye, three times a day, for four days. Then 
a second test was made. 

The ophthalmometer gave the same readings as at the first 
test. 

Test cards and trial 



R. V. = 2V0 • f* ^^- + 2 D. cyl., 90° -2D. cyl., 180°. 
L. Y.=^-^: I^W. +25D. +1.50D. cyl., 90°. 

Ophthalmoscope. —B.. 2D. at 180° and M. 2.50 D. at 90' 
right eye ; Em. at 90° and H. 1.50 D. at 180° left eye. 



180 




R. E. 



L. E. 



Fig. 81. 



Ten days later, when the effects of the atropine had left the 
eyes, a third test was made. The ophthalmometer read uni- 



192 THE REFRACTIOX OF THE EYE 

formly with the two previous tests, and the subjective test, 
with the test cards and trial lenses, resulted in the patient 
accepting the same glasses as when under the influence of atro- 
pine, except that the +.25 D. sphere was not accepted by the 
left eye. They were accordingly ordered, a cross-cylinder 
+ '2 D. cyL, 90° -2 D. cyl., 180° right eye, and + 1.50 D. 
cyl., 90° left eye. The cross-cylinders in the right eye gave a 
broader field and more clearly defined the letters than either of 
the sphero-cylinders into which it could be converted. How- 
ever, had either of the sphero-cylinders been given, it would 
have been the minus sphere with plus cylinder, so that the 
cylinder would have corresponded both in character (plus) and 
in direction of axis (90°) with the cylinder in the opposite eye. 

Case LXXVI. Mixed astigmatism luitli the rule left eye; 
Compound hypermetropic astigmatism luith the rule right eye; 
Asthenopia; Relief tuith glasses.' — July 2, 1895, Ida S., aged 
thirty years, in good health, but has suffered considerably with 
headaches since a schoolgirl. She has had numerous glasses, 
but none have been comfortable or relieved the headaches. 

Ophthalmometer. — Astigmatism with the rule, ID., axis 
75°+ or 165°- right eye ; 3 D., axis 120°+ or 30°- left eye. 

Test cards and trial lenses. — 

R. y. =||_: ffW. +.25D. + .50D. cyh, 75°. 

L. V. =2^^ : I^W. +1.25D. cyl., 120°-1.25D.cyL,30°. 

Reads Jaeger No. 1 from 5 to 20 inches. 

Ophthalmoscope. — YL. ID. right eye; H. 1.50 D. at 30° 
and M. 1.50 D. at 120° left eye. 

Second test : this resulted in the patient accepting exactly 
the same glasses as at the first test, and they were ordered : — 

+ .25 D. + .50 D. cyl., 75° right eye ; 
-1.25 D. + 2.50 D. cyl., 120° left eye. 



ILLUSTRATIVE CASES 



193 



In this case, as the mixed astigmatism was not of large 
amount and was equally divided between hypermetropia and 
myopia, I converted the cross-cylinder into a sphero-cylinder, 




120' 




R. E. 



L. E. 



Fig. 82. 



a minus sphere with a plus cylinder, so that the cylinder would 
correspond in character (plus) with the cylinder in the opposite 
eye. 

These glasses have been worn with great comfort. 

Case LXXVII. Mixed astigmatism tvith the rule left eye; 
Simple myopic astigmatism ivitli the rule right eye ; Amblyopia ; 
Asthenopia; Relief with glasses. — January 9, 1894, George B., 
aged thirty-five years, in good general health, but has been 
greatly troubled with his eyes for many years. He is com- 
pelled to hold reading matter too close to his eyes, and after 
using the eyes for close work, vision becomes painful and often 
headaches follow. 

Ophthalmometer. — Astigmatism with the rule in each eye, 
3.50 D., axis 105° -|- or 15°- right eye; 5 D., axis Sd°-{- or 
175°- left eye. 



194 THE REFRACTIOX OF THE EYE 

Test cards and trial lenses. — 
^- ^- = M • f^^^- - SD. cyl., 10°. 



L. Y. 



_2_0 

100 • 50 



: I^AV. +2D. cyl., 80°- 2.50 D. cyl.,lW 



Reads Jaeger No. 1 from 6 to 12 inclies. 
Ophthalmoscope. — ^L 3.50 D. at 100° and Em. at 10° right 
eye ; M. 3 D. at 80° and H. 2D. at 170° left eye. 





R. E. 



L. E. 



Fig. 83. 



Second test : after using an astringent wash for a week, a 
second test was made. 

Ophthalmometer. — Astigmatism with the rule, 3.50 D., 
axis 100° + or 10°- right eye; 5 D., axis 80°+ or 170° - left eye. 

The subjective test resulted in exactly the same glasses 
being accepted as at the first test, and they were ordered : — 

-3D. cyl., 10° right eye ; 

+ 2 D. cyl., 80° - 2.50 D. cyl., 170° left eye. 

Here, again, I did not convert the cross-cylinder into a 
sphero-cylinder, because the astigmatism was large in amount,. 



ILLUSTRATIVE CASES 195 

and because by actual trial of both the sphero-cylinders into 
which it could be transposed, the patient saw better with the 
cross-cylinder. Had I given a sphero-cylinder, it would have 
been a plus sphere with a minus cylinder, in order that the 
cylinder should correspond in character to the myopic cylinder 
in the opposite eye. 

Case LXXVIII. Mixed astigmatism with the rule left eye ; 
Simple myopic astigmatism with the rule right eye ; Asthenopia ; 
Fitted to glasses without atropine^ although the child was but eight 
years old; Relief with glasses. — February 7, 1893, William G., 
aged eight years, is in good health, but has been troubled with 
headaches at school. He complains also of not being able to 
see the blackboard. 

Ophthalmometer. — Astigmatism with the rule, 3.50 D., 
axis 105° + or 15° - right eye ; 2.75 D., 75° + or 165° - left eye. 

Test cards and trial lenses. — 

R- V. = 2V0 + : I* W. - 3 D. cyl., 15°. 

L. V. = 2V0+ :|^W. + 1.25D. cyl., 75°-. 75 D. cyL, 165°. 

Ophthalmoscope. — M. 3.50 at 105° and Em. at 15° right eye ; 
M. 1 D. at 75° and H. 1.50 D. at 165° left eye. 

Second test : after using an astringent wash for a mild 
conjunctivitis, a second test for glasses was made. The test 
corresponded exactly in every way with the first test, and 
the glasses were ordered : — 

— 3D. cyl., 15° right eye ; 
+ 1.25 D. - 2 D. cyl., 165° left eye. 

These glasses have been worn for more than five years, and 
with relief of headaches and other asthenopic symptoms. 

The tender age of this patient, eight years, would seem to 
call for a mydriatic, especially when it w\as found that mixed 
astigmatism was present ; nevertheless, he was fitted without 



196 



THE REFRACTIOX OF THE EYE 



it. The axis of the glass corresponded exactly with the axis 
indicated by the ophthalmometer in each eye ; but in the left 
eye .75 D. ^Yas deducted from the amount instead of the usual 
.50 D., as ordinarily in astigmatism with the rule. 

The cross-cylinder was converted into a sphero-cylinder, a 
plus sphere with a minus cylinder, in order that the cylinder 




165 




R. E. 



L. E. 



Fig. 84. 



might correspond in axis and character with the simple myopic 
cylinder of the right eye. This made a slightly heavier glass 
than a sphero-cylinder with a minus sphere and a plus cylinder, 
but the importance of having both cylinders alike much out- 
weighed the slight disadvantage in weight. 

Case LXXIX. 3Iixed astigmatism with the rule right eye; 
Compound myopic astigmatism with the ride left eye; Constant 
pain in the eyes; Relief tvith glasses. — Fehvimry 23, 1892, Ella 
M., aged twenty-three 3-ears, in good health, came to the clinic 
of Drs. Roosa and Lewis at the :\Ianhattan Eye and Ear 
Hospital, and was referred to me for treatment. She com- 
plained of severe pain in the eyes when she attempted close 



ILLUSTRATIVE CASES 



197 



work of any kind, and this has been so since a child. She is 
the only member of her family troubled with her eyes. 

Ophthalmometer. — Astigmatism with the rule, 3D., axis 
75°+ or 165°- right eye; 3D., axis 105°+ or 15°- left eye. 

Test cards and trial lenses. — 



R.V. = 



200 



20 
TO 



+ W. + 1 D. cyl., 75° - 1.25 D. cyl., 165^ 



L V = -^- 

^' ^ • — 200 



10 *^ ' 



5D.-2.50D. cyL, 15°. 
Reads Jaeger No. 1 from 6 to 12 inches. 



165 




R. E, 




Fig. 85. 



L. E. 



Ophthalmoscope. —M. 150 D. at 75° and H. 1.50 D. at 165° 
right eye ; M. 7 D. at 105° and M. 3 D. at 15° left eye. 

Second test : two days later the ophthalmometer gave the 
same reading as at first. 

Test cards and trial lenses. — 

^' ^- = 2^ • I* - W. + 1.25 D. cyl., 75° -ID. cyl., 165°. 
L V = -2_iL . _2j)_ w _ J. D — *^ D PA 1 1 \° 

-^•^•200*100 ^^ ' •* J-'. — -J !>'. C}1., lO . 

This last glass was ordered, the cross-cylinder in the right 
eye being converted into a sphero-cylinder ; a plus sphere with 



198 THE REFRACTIOX OF THE EYE 

a minus cylinder, in order that the cylinder should correspond 
in character and axis with the cylinder in the opposite eye. 
Ordered : — 

+ 1.25 D. - 2.25 D. cyl., 165° right eye; 
- 4 D. - 2 D. cyl., 15° left eye. 

These glasses gave immediate relief from her asthenopic symp- 
toms. After a few weeks' time she dropped out from under 
observation. 

In this case, as in the one reported immediately preceding 
it, the cross-cylinder was converted into a sphero-cylinder, plus 
sphere with a minus cylinder, rather than into a minus sphere 
and a plus cylinder. This made a little heavier glass, but the 
disadvantage was more than counterbalanced by having the cyl- 
inders correspond in character and axis. And by actual trial 
in the frames, before either glass was ordered, the patients pre- 
ferred the plus sphere with a minus cylinder. 

Case LXXX. Mixed astigmatism with the rule in each eye^ 
with the axes slanting b° from the vertical and horizontal meridians 
in the same direction in each; Asthenopia; Relief ivith glasses. — 
January 21, 1896, D. L. B., in excellent health, but has suffered 
a great deal with his eyes since a child at school. Headaches, 
blurring of the vision, burning of the eyelids and pains in 
the eyes, were some of the symptoms of which he complained. 
He has had numerous glasses prescribed, none of which proved 
satisfactory. 

Ophthalmometer. — Astigmatism with the rule, 3D., axis 
95° + or 5° — in each eye. 

Test cards and trial lenses. — The lines on the clock-dial 
were all seen about equally well with each eye, but indistinctly 
before the test was begun. When the plus cylinder was put 
on, the vertical lines showed the plainest, and when the final 
full amount of minus cylinder was added to the plus cylinder, 



ILLUSTRATIVE CASES 



199 



the horizontal lines also came out plainly, thus with the cross- 
cylinders all of the lines on the clock-dial were brought out 
plainly and evenly. 

R. V. = 2% : 1^ W. -f- 1.50 D. cyl., 95° - 1.50 D. cyl., 5°. 
L. V. = 2% • M W. + 1.25 D. cyL, 95° - 1.25 D. cyl., 5°. 

Reads Jaeger No. 1 from 3 to 16 inches. 

Ophthalmoscope. — M. 1.50 D. at 95° and H. 1.50 D. at 5° 
in each eye. 

Second test : one day later the ophthalmometer showed the 
same reading. 

Test cards and trial 



R V — -2-0- 

^' ^ • ~ 200 



20. 
20 



1.25D. cyL,5°. 
1.25 D. cyl., 5°. 



+ W. +1.50 D. cyl., 95^ 
L. V. = ,2_o_ : _2_o_ + w. + 1.50 D. cyl., 95^ 

A third test confirmed this second, and the glasses were 
ordered as cross-cylinders. Cross-cylinders were prescribed 
because they defined the letters 
better and felt easier to the eyes 
than either sphero-cylinder into 
which they could be converted. 
After wearing the glasses con- 
stantly for a week the doctor 
got relief from his asthenopic 
symptoms. I have had him 
under observation for more than 
two years, and he wears the 
same glasses with continued re- 
lief. It is comparatively a rare 
occurrence for the axes of an 
astigmatism in the two eyes to 
slant in the same direction from 

the horizontal and vertical meridians ; and when it does hap- 
pen, usually, the asthenopia is more marked in such cases than 




Fig. 86. 



200 THE REFRACTION OF THE EYE 

in those cases where the axes slant an equal number of degrees 
in opposite directions from the vertical and horizontal merid- 
ians. For example, say the axis in each eye slants 15° toward 
the temple from the vertical meridian, in which case, in hyper- 
metropic astigmatism, the cylinder would be worn at 105° right 
ej^e, and at 75° left eye. In the present case both axes stand 
at 95°, slanting toward the temple in the right eye, and toward 
the nose in the left eye, or in the same direction. ^ 

Case LXXXI. Mixed astigmatism against the rule right 
eye; No corneal astigmatism left eye^ hut the patient accepts a 
weak cylinder against the rule ; Patient is very nervous ; Marked 
asthenopia; Relief with glasses. — June 27, 1894, Mary M., aged 
twenty-six years, in only fairly good health, and is very nervous. 
Her eyes have given her much trouble for the last four years, 
especially the right. She finds it almost impossible to use the 
eyes for close work of any kind. Not only do the eyes ache, 
but also her head, and often she becomes very nervous and irri- 
table. Her mother died of consumption, but her father is still 
living and in good health. He wears very strong sphero-cyl- 
inders, while two brothers and a sister of the patient also wear 
cylindrical glasses. 

Ophthalmometer. — Astigmatism against the rule, 3 D., axis 
175° + or 85° — right eye. No corneal astigmatism left eye. 

Test cards and trial 



R. V. = 2^0 • M W- + 2.50 D. cyL, 175°. 
L- V. = IJ : \% -W. + .25 D. cyl., 15°. 

Reads Jaeger No. 1 from 6 to 14 inches. 
Ophthalmoscope. — M. 1 D. at 90° and H. 2 D. at 180° right 
eye ; H. 50 D. left eye. 

1 For the relative position of the axes of astigmatic glasses, see Claiborne, 
New York Med. Journal, June 25, and July 2, 1892 ; Knapp, Trans. Amer. 
Ophthal. Sac, Bd. Vol. VI, p. 308, 1892 ; and Snellen, Graefe's Arch. Ophthal., 
Vol. XVI . No. 2, p. 200, 1869. 



ILLUSTRATIVE CASES 



201 



On account of a conjunctivitis an astringent wash was 
ordered, and after one week a second test was made. The 
ophthalmometer read the same as at the first test. 

Test cards and trial lenses. — 

R. V. = 2% • f^ W. + 2.50 D. cyL, 175° - .50 D. cyl., 85°. 
L. V. = |o : 10 w. _^ .25 D. cyl., 15°. 

The ophthalmoscope agreed essentially with the first ex- 
amination. 





R. E. 



Fig. 87. 



L. E. 



A third test was made, and as it agreed with the second, 
this last glass was ordered, a simple cylinder in the left eye, 
4- .25 D. cyl., 15°, and a sphero-cylinder, — .50 D. + 3 D. cyl., 
175° right eye. In converting the cross-cylinder into a 
sphero-cylinder I gave a minus sphere and a plus cylinder. 
This made a light glass, and at the same time the cylinder cor- 
responded with the cylinder in the opposite eye. A plus 
sphere and a minus cylinder in this case is not to be thought 
of, because it would be heavy, and the cylinder would not 
correspond with the cylinder in the opposite eye. 

In this case in the right eye the patient accepted all of the 



202 THE REFRACTION OF THE EYE 

astigmatism, no lenticular astigmatism being present. In the 
left there was no corneal astigmatism, but the patient accepted 
a weak plus cylinder against the rule. 

It took the patient between three and four weeks to become 
accustomed to the glasses, but after that time she wore them 
with comfort and relief from asthenopia. At times she is 
nervous, but is much relieved in this respect. I saw her from 
time to time for a number of months, and the glasses con- 
tinued to be satisfactory. 

Case LXXXII. Mixed astigmatism against the rule in each 
eye ; Spasm of accommodation ; Marked asthenopia ; Relief with 
glasses. — August 11, 1894, Jennie F., aged twenty-eight years, 
in good health, consults me on account of headaches and pains 
in the eyes. She has had more or less trouble with her eyes 
since childhood. There is a well-marked conjunctivitis present. 

Ophthalmometer. — Astigmatism against the rule, 3D., axis 
155° -f- or 65°- right eye ; 2 D., axis 175°-}- or 85°- left eye. 

Test cards and trial lenses. — 

^- ^- = 1^ • f^ W. + 1.50 D. cyl., 155° - 1.50 D. cyl., 65°. 
L-V. = f^ :f^W. -}- .75 D. cyl., 175°- .50 D. cyl., 85°. 

Reads Jaeger No. 1 from 6 to 17 inches. 

Ophthalmoscope. —Isi. 1.50 D. at 150° and H. 1.50 D. at 
60° right eye ; M. 1 D. at 180° and H. 1 D. at 90° left eye. 

During the test, especially with the left eye, the patient 
would at one time accept a certain glass, then refuse it. Again, 
the vision at one moment would be very good, then the next 
moment poor. Thus, spasm of accommodation was clearly 
present. Examination of the muscles failed to show any 
insufficiencies. There was a well-marked conjunctivitis present, 
and this was treated for ten days, after which a second test 
was made. 

Second test : the ophthalmometer gave the same reading 
in the right eye as at the first test ; and the same amount of 



ILLUSTRATIVE CASES 



203 



astigmatism in the left eye as at first, but with the axes at 
exactly 180° and 90°. 

Test cards and trial lenses. — 

R. V. = ^-^% : 1^ W. + 1.50 D. cyl., 155° - 1.50 D. cyL, 65\ 
L. V. = 1^ : f^ W. + 1.50 D. cyl., 180° - .50 D. cyL, 90°. 

Ophthalmoscope. — Showed about the same condition as at 
the first test. 

65° 90° 





R. E. 



L. E. 



Fig. 



A third test was given which agreed with the second, and 
the glasses were ordered as sphero-cylinders, minus spheres 
with plus cylinders : — 

-1.50 D. +3 D. cyl., 155° right eye; 

- .50 D. + 2 D. cyl., 180° left eye. 

In the left eye this was a lighter glass than a plus sphere 
with a minus cylinder, while in the right eye it made no differ- 
ence. 

Thus far, about four years, these glasses have been worn 
with comfort. 



204 



THE REFRACTIOISr OF THE EYE 



Case LXXXIII. Mixed astigmatism of small amount 
against the rule in each eye ; Presbyopia ; Asthenopia ; Blepha- 
ritis ; Relief of asthenopia and blepharitis ivith glasses. — Septem- 
ber 25, 1892, Henry C, aged forty-eight years, in good healtii, 
has been troubled with his eyes for five or six years when 
using them for close or prolonged work. The eyelids get red 
also if he persists in using the eyes, and, at times, headaches 
follow. 

Ophthalmometer. — Astigmatism against the rule, .50 D., 
axis 10°+ or 100°- right eye; .50 D., axis 165° -f or 75°- 
left eye. 

Test cards and trial 



^'^'=i^''U ^^' + -50 D. cyl., lO*' - .25 D. cyL, 100^ 
L. V. = 1^ : f^ W. + .50 D. cyl., 165° - .25 D. cyl., 75°. 

Ophthalmoscope. — H. .50 D. in each eye. The myopic 
astigmatism was too small to estimate. The foci of the two 
chief meridians, according to the glasses accepted, can be seen 
from the following figure : — 





R. E. 



L. E. 



Fig. 89. 



ILLUSTRATIVE CASES 205 

Two days later a second test was made, which corresponded 
in every particular with the first. 

It will be noticed that the myopic portion of the glasses 
accepted by the patient is very small, only .25 D., and I find 
in the record of the case in my case-book the following note : 
"The — .25 D. cyl. when added to the -f .50 D. cyl. increases 
the vision more than a line, or from |^— to |-2-." Usually a 
.25 D. cylindrical glass does not improve vision so much, but 
in this case the astigmatism was against the rule and at an off 
axis (slanting), and that may account for its marked effect in 
the improvement of vision. 

The patient would not wear glasses for the distance, though 
they improved the vision very much. Incidentally it may be 
remarked here, that many even intelligent people are content 
with poor distant vision, and will not wear glasses except for 
near work. Some, because they do not wish to be bothered 
with two' pairs of glasses ; some refusing to wear glasses on the 
street from vanity, perhaps. 

On account of his presbyopia, he being forty-eight years of 
age, it was necessary to give him reading glasses. I allowed 
+ 1.75 D. for his presbyopia. After having converted his dis- 
tance cross-cylinders into sphero-cylinders, — .25 D. + .75 D. 
cyl., 10° right eye, and - .25 D. + .75 D. cyl., 165° left eye, 
it was an easy matter to add the -f- 1.75 D. sphere to them 
algebraically, which would give -h 1.50 D. + .75 D. cyl., 10° 
right eye, + 1.50 D. + -75 D. cyl., 165° left eye. 

The glasses were ordered, and have been worn for five years 
without change. They relieved him of his blepharitis entirely, 
and made close work comfortable, though for the last few 
months he has felt the want of a stronger glass. 

A simple increase in the spherical part of his glass will, of 
course, be all that is necessary. 

This case naturally brings up the question of transposition 
of glasses in mixed astigmatism made necessary by presbyopia. 



206 THE REFRACTIOX OF THE EYE 

I may say the transposition is made easier if the cross-cylinders 
are first converted into sphero-cylinders, as in the last case, 
then the presbyopic part added to them algebraically. Since 
this method of transposition has already been explained at 
length, under the lines given to myopia and myopic astig- 
matism, I shall not go here into the subject again except to 
give one or two examples. 

In the last case reported here, for example, the change in 
the glasses made necessary by the presence of the 1.75 D. of 
presbyopia is made quite plain by a glance at Fig. 89 and the 
following diagram of cross-lines. Those who are in doubt as 
to the correctness of any combination of glasses they have 
made by the abstract algebraic equation, may resort to this 
method of drawing the sections of the two chief meridians 
of each eye with their foci, together with the simple cross-lines 
denoting those meridians, at the ends of which are marked the 
refractive power of each meridian in diopters. Then note the 
effect on the foci that any given amount of presbyopia will cause- 

For instance, in Fig. 89, illustrating the last case, right eye, 
the meridian at 100° is hypermetropic by .50 D., and the focus 
is .50 D. back of the retina (+ .50 D. added to + 1.T5 D. = 
-h 2.25 D.); while the meridian at 10° is myopic by .25 D. 
with the focus to that. extent in front of the retina, and the 
presbyopia of 1.75 D., for reading distance, would put the 
focus in this meridian but 1.50 D. back of the retina (— .25 D. 
added to -f 1.75 D. = -f- 1.50 D.), that is, the m3-opia of .25 D. 
neutralizes that amount (.25 D.) of the presbyopia. From this 
it is quite evident, for reading purposes, the eye has been con- 
verted into a compound hypermetropic astigmatism, the merid- 
ian at 100° being 2.25 D. presbyopic, and that at 10°, 1.50 D. 
In order to correct this, a -f 1.50 D. sphere, combined with 
-}- .75 D. cyl., 10°, is necessary. This, in fact, was ordered. 
Like changes took place in the left eye, as will be seen by look- 
ing at Figs. 89 and 90. 



ILLUSTRATIVE CASES 



207 



I have presented these cases of mixed astigmatism in their 
various forms at some length, for the purpose of showing that 
even these difficult cases may be fitted, in most instances, with- 
out the aid of a mydriatic. The cases here presented are not 
selected ones. The indications for the use of a mydriatic in 
these cases are exactly the same as in others of refractive error, 
to wit, lack .of uniformity in tests, spasm of accommodation, 
and so forth. 




R. E. L. E. 

Fig. 90. — Showing the effect of a presbyopia of 1.75 D. on the near-point in the case 
just reported. See Fig. 89 for the distance focus. 

The amblyopia present in most cases of mixed astigmatism 
is the one great stumbling-block for many observers, and serves 
to induce them to use a mydriatic whether there are any other 
indications for its use or not. In regard to amblyopia, a certain 
amount of it is to be looked for in most cases of astigmatism, 
especially if the astigmatism is large in amount ; consequently, 
we should not expect to bring vision up to normal, |§, or nearly 
so, in all cases. If the patient accepts the same glasses on two 
or three successive tests, and they correspond Avith the objective 
tests, we may give the glasses Avithout hesitation. 

In order to make myself doubly sure that I am not giving 



208 THE KEFRACTION OF THE EYE 

too weak plus, and too strong minus, cylinders in these cases, 
after I have tested each eye separately, I then put the glasses 
on as accepted and uncover both eyes. With both eyes uncov- 
ered, I increase the plus cylinder .25 D. in strength, to see if 
the vision can be improved by the change, and I also diminish 
the minus cylinders .25 D. to find if vision can be improved. 

Another point I wish to insist upon is, that the test should 
be conducted methodically and quickly, and the patient kept 
not over thirty minutes in any one test. Have the patient 
come back two, three, or four times, if necessary, but do not 
worry him for an hour or two at a time in the vain attempt 
to get perfect vision. Because : first, as asserted above, many 
times perfect vision is not to be had, whatever means, mydri- 
atics or what not, are employed to secure it ; second, if the test 
is very prolonged, the patient grows tired, becomes confused in 
his replies, spasm of accommodation is incited, and the observer 
himself gets disgusted and orders a mydriatic, not knowing what 
else to do, perhaps. If after two tests, of not more than thirty 
minutes" duration, the tests do not approximately agree, and 
there is a tendency to, or an actual, spasm of accommodation, 
I then order a mydriatic, but not until then. 

In all of these cases the routine method of beginning the 
test with weak plus glasses and gradually increasing them in 
strength until the vision begins to be made worse, and then try- 
ing minus cylinders at right angles to the plus as long as they 
improve vision, is followed. The test should never under any 
circumstances be begun with minus cylinders, because if it is, 
the patient, nine times out of ten, will accept the full amount of 
the astigmatism in minus cylinders. While these glasses might 
be worn for a few weeks or months even with comparative com- 
fort, yet after a short time they would have to be changed, as 
the patient would gradually relax his accommodation. There- 
fore, the necessity of avoiding the mistake of beginning the 
test incorrectly is apparent. 



CHAPTER VIII 

lEREGULAR ASTIGMATISM — CONICAL CORNEA — HYPERBOLIC 
LENSES — CONTACT LENSES — ILLUSTRATIVE CASES 

Before the days of the perfected ophthalmometer, in no 
class of cases did we have more difficulty in fitting glasses, 
even with tolerable satisfaction, than in those with irregular 
curvature of the cornea, due to opacities, conical cornea, and 
so forth. Thanks to the efforts of Javal and Schiotz, who 
made the ophthalmometer a practical office instrument, we now 
sometimes score our greatest triumphs in just such cases. The 
disk of Placido, attached to the 1889 model of the ophthalmom- 
eter, aids greatly in detecting irregularity of surface on the 
cornea ; and, for this one reason, if for no other, should not be 
removed from the instrument, as suggested and actually done 
by some of my American confreres. In cases of conical cornea, 
especially are the concentric circles on the disk and the disk 
itself of marked service in giving us the general shape of the 
cornea and the topography of the cornea at any special point 
on it. Furthermore, by having the patient look at a point a 
certain number of degrees from the center of the disk, as 
marked on the circles drawn on the disk in conjunction with 
the radii drawn from the center of the disk, we can measure 
the radius of curvature of the cornea in its two chief meridians 
at that number of degrees from its center, but on the opposite 
side from which the patient is looking. For example, if we 
cause the patient to look directly upward at a point of cross- 
ing of the circle marked 20°, and the radiating line extend- 
ing directly upward, we measure a point on the cornea 

209 



210 THE REFRACTION OF THE EYE 

20° below its center. And so for any other point on the 
cornea. 

Again, the circular lines on the disk give us important 
information as to the condition of the surface of the cornea, 
not only as to irregular astigmatism, as manifested by irregu- 
larity and distortion of these circular lines, but as to the pres- 
ence of regular astigmatism, when present in large amount 
with it, as manifested by an elongation of these circles in the 
direction of the meridian with the longest radius of curvature. 
I may say in this place that Reid's ophthalmometer is a most 
valuable little instrument in detecting irregular astigmatism 
and conical cornea of small amount, and for the following 
reason : In Reid's instrument, the two images looked at are 
two circles, or, rather, one circle doubled by means of a prism, 
and the least irregularity of the surface of the cornea is quickly 
detected by these circles becoming irregular in outline. At 
the same time, if regular astigmatism is present, it indicates it 
by the circles becoming elliptical in shape. In conical cornea 
of moderate amount, if a suitable prism is put in the telescope 
of the instrument, this instrument is very valuable. The 
reader is referred to the Appendix of this book for a descrip- 
tion of the instrument and its use. 

Again, in the Javal-Schiotz instrument, the images of the 
mires themselves are of service in detecting irregular astigma- 
tism, on the same plan as Wecker's squares, that is, by their 
distortion and irregularity of outline when irregular astigma- 
tism is present. It is also shown when there is no position on 
the cornea where the lines dividing them through the center 
can be made to form one continuous straight line. However, 
if regular astigmatism is present in addition to the irregular, 
there are two positions on the cornea at which these lines 
become more nearly straight than elsewhere, thus indicating 
the axis of the regular astigmatism. 

So delicate a test is this distortion of the images of the 



IRREGULAR ASTIGMATISM 211 

mires, that the slightest irregularity of the surface of the cor- 
nea is detected. This leads to a close inspection of the cornea 
by oblique illumination, and the detection of minute opacities, 
which otherwise would be overlooked at times. 

The ophthalmometer, together with the disk of Placido, is 
also of the greatest value in finding the most regular part of a 
cornea affected with central opacity or leucoma, or, in case of 
conical cornea, behind which to perform an iridectomy for 
visual purposes. It is of the utmost necessity to place the 
iridectomy behind the clearest and most regular portion of the 
cornea in such cases. Not only is the ophthalmometer of 
value in detecting this best place on the cornea, but it will 
detect and measure any regular astigmatism present at such 
place. For example, if in a given case we have found the por- 
tion of the cornea directly inward from the center (right eye) 
to be the clearest, and have accordingly performed an iridec- 
tomy for visual purposes, and later wish to fit the eye for 
glasses. To measure this portion of the cornea, we cause the 
patient to turn the eye directly outward about 15° (letting him 
look at the point of crossing of the 15° circle and the hori- 
zontal radiating line), and ascertain the regular part of the 
astigmatism. In this way, the fitting of the correct and best 
glass is greatly facilitated. Indeed, what was at one time a 
most tedious, • and, in many instances, a hopeless task — the 
fitting of glasses in irregular astigmatism — is reduced, by the 
aid of the ophthalmometer and Placido's disk, to a scientific 
and definite result. 

Some concrete cases will illustrate the above points. 

Case LXXXIV. Slight irregular astigmatism due to opac- 
ities of the cornea; Regular astigmatism; Amblyopia ; Astheno- 
pia. — January 4, 1898, Pauline G., aged eleven years, in good 
general health, came to the clinic of Drs. Lewis and Van Fleet, 
at the Manhattan Eye and Ear Hospital, and was assigned to 
ane for treatment. The patient's mother says that her child's 



212 THE REFRACTION OF THE EYE 

eyes were slightly inflamed when a baby. She has complained 
of poor and painful vision since she entered school. The patient 
has always appeared to be near-sighted. 

On looking at this patient's eyes without oblique illumina- 
tion, no opacities can be seen, and nothing of a peculiar char- 
acter appears to the observer. 

Ophthalmometer. — Regular astigmatism with the rule, 1.50 
D., axis 90° + or 180° - right eye ; 1.25 D., axis 75° + or 165° 

— left eye. Irregular astigmatism in each eye, as made mani- 
fest by dimness and irregularity of the outlines of the images 
of the mires, and by the line dividing the mires into halves 
(guide-lines) not being clear-cut in any position, but dim and 
wavy in appearance. The concentric circles on the Placido 
disk were dim and irregular in outline also. 

Test cards and trial lenses. — 

^•^•=H:f* W. 4-1 D. cyl., 90°. 
L. V. =|^:f^-W. -I- .75 D. cyl., 75°. 

Reads Jaeger No. 1 from 3 to 15 inches. She has a desire 
to hold the print too close. 

Ophthalmoscope. — Em. at 90° and H. 1 D. at 180° right 
eye ; Em. at 75° and H. .50 D. at 165° left eye. Oblique illu- 
mination of the cornese showed opacities of a diffuse nature in 
each. 

Second test : four days after the first test a second one was 
made, and as the patient accepted exactly the same glasses as 
at first, they were ordered. When last seen, about two months 
after being fitted, the glasses were giving satisfaction, and the 
patient was able to pursue her studies with comfort. 

Case LXXXV. Irregular astigmatism associated with a 
large amount of regular astigmatism folloumig perforating ulcer 
of the cornea ; Marked decrease both of the irregular and regular 
astigmatism^ with attendant increase of vision in one year's time. 

— This is a most interesting case, because of the changes that 



IRREGULAR ASTIGMATISM 213 

occurred in the shape of the cornea after the ulcer had healed, 
which were studied by means of the ophthalmometer, and 
noted for a long period. I give a brief history of the case : — 

Mr. D. L., aged thirty-two years, first came under my care 
September 13, 1893, for treatment for ulcerative keratitis with 
hypopion, which was due to an injury from a piece of iron from 
a chisel. A large sloughing ulcer covered the lower half of the 
cornea, extending up almost to the center of the cornea, and 
the anterior chamber was half full of pus. With paracentesis, 
atropine, hot water and bandage, the patient recovered in two 
weeks' time, but not without the ulcer perforating. Fortu- 
nately, the pupil was well dilated before perforation occurred, 
so there was no prolapse of iris, and the pupil was circular, 
central, and active after the effects of atropine wore off. At 
time of discharge of the patient from the hospital he could see 
the hand at 2 feet distance only. 

November 4, a little over a month after his discharge from 
the hospital, I examined his eye carefully with the ophthal- 
mometer and with the lenses. I may say at this time that the 
eye was perfectly white, the pupil central and active, and the 
lower outer quadrant of the cornea had a dense opacity cover- 
ing it, while the lower inner quadrant had a diffuse opacity 
extending to the level of the lower edge of the pupil. The 
patient stated that his vision was much improved. 

Ophthalmometer. — The right eye had .50 D. astigmatism 
with the rule, axis 120° + or 30° — ; left eye showed marked 
irregular astigmatism, with a large amount of regular astigma- 
tism with the rule, 12 D., axis 45° + or 135° — . 

Test cards and trial lenses. — 

R. V. = |§ : not improved. 

L. V. = jV% : T^iL W. - 9 D. cyl., 135». 

Ophthalmoscope. — H. 1 D. right eye; the fundus in the 
left eye is seen indistinctly, the outline of the disk is irregular, 



214 THE REFRACTION OF THE EYE 

and the blood vessels distorted and partly seen ; that is, a por- 
tion of a vessel would be seen well one moment and lost the 
next, if either the ophthalmoscope or patient's head moved. 

February 18, 1894, three months later, a second test was 
made. 

Ophthalmometer, — The astigmatism was the same as at the 
first test in the right eye ; irregular astigmatism, not so marked 
as before, and regular astigmatism against the rule, 8.50 D., 
axis 15° + or 105° - left eye. 

Test cards and trial lenses. — 

R. V. = 1^ + : not improved. 

L- V. = 2%<V : iVo + W. - 7.50 D. cyl., 105°. 

November 9, 1894, a little over a year after the first exam- 
ination, the following remarkable improvement was noted : — 

Ophthalmometer. — Test the same in the right eye as before ; 
moderate amount of irregular astigmatism with regular astig- 
matism with the rule (as on the first test), 3D., axis 45° -{- or 
135° - left eye. 

Test cards and trial lenses. — 

R. V. = 1^ + : not improved. 

L- V. = i^A - : H W. - 8 D. cyl., 135°. 

I had this patient under observation for about fifteen months. 
The most interesting feature of the case was the remarkable 
change in the character and amount of the astigmatism in the 
left eye. Twelve diopters of regular astigmatism with the rule 
associated with marked irregular astigmatism changed in a 
little over three months' time to 8.50 D. against the rule; and 
then in nine months the regular astigmatism diminished to 
3 D. with the rule., and back to the same axis exactly as at first, 
and with marked improvement in the irregular astigmatism. 

Without the aid of the ophthalmometer, it would have been 
almost impossible to note these changes and to make the correct 



IRREGULAR ASTIGMATISM 215 

tests for vision. With it, it was comparatively easy, and the 
fact was demonstrated to him, that he had useful vision in the 
left eye, should he lose the right. This was naturally a source 
of great comfort to him. 

Case LXXXVI. Irregular astigmatism associated with regu- 
lar astigmatism against the rule right eye ; Regular astigmatism 
against the rule left eye ; Asthenopia ; Relief with glasses. — June 
1, 1894, Mrs. L. T. S., aged forty-one years, is in fairly good 
general health, has had more or less trouble with her eyes for 
the last four years. Twelve years ago she was very much run 
down in health and could not use her ej^es for close work for 
about two months. She thinks her eyes were weakened when 
a child, from an attack of measles. She has headaches now 
and pain in the eyes if she sews or reads. 

Ophthalmometer. — Irregular astigmatism to a moderate degree 
with regular astigmatism against the rule, .50 D., axis 135° -|- 
or 45° — right eye ; regular astigmatism against the rule, 3D., 
axis 150° + or 60° - left eye. 

Test cards and trial 



R. V. = f^ : 1^ - W. + 1 D. + .50 D. cyl., 135°. 
L. V. = |§ : 1^ - W. + 2.75 D. cyl., 150°. 

Reads Jaeger No. 1 from 7 to 16 inches. 

Ophthalmoscope. -^YL. 2D. at 45° and H. 1 D. at 135° right 
eye; H. 3 D. at 60° and Em. at 150° left eye. The fundus in 
the right eye was made somewhat indistinct by the faint corneal 
opacities, and the estimation of the error of refraction by the 
ophthalmoscope made doubtful. 

Second test : two days later, a second test was made in which 
the ophthalmometer gave the same readings as at the hrst test. 

Test cards and trial lenses. — 

R. V. = f§ : 1^ W. -f- 1.25 D. + .75 D. cyl., 135°. 
L. V. = II : II - W. + 2.75 D. cyl., 150°. 



216 THE REFRACTION OF THE EYE 

This last glass was ordered, and gave her almost entire relief 
from her headaches. 

The ophthalmometer was of especial yalue in this case in 
ascertaining the regular astigmatism present in the right eye, 
in conjunction with the irregular. Although the vision could 
not be brought up to the normal, as in the other eye which had 
much more regular astigmatism, it was greatl}^ improved. The 
amblyopia in the right eye in this case can be accounted for in 
the main by the presence of faint opacities in the cornea, as the 
fundus of the eye was normal. It would have been folly to 
put atropine in such an eye, as the patient was over forty years 
of age. 

Case LXXXVII. Irregular astigmatism in each eye; Large 
amount of regular astigmatism in each eye of the mixed variety ; 
Severe asthenopia ; Vision considerably improved and asthenopia 
relieved with the correcting glasses. — January 28, 189-i, Bertha 
G., aged twenty-one years, general health only moderately 
good, has had trouble with her eyes since a child, following an 
attack of measles. Three years ago had an attack of la grippe., 
which weakened her general strength very much, and since then 
she has had recurrent ulcers on the margins of the cornea in 
each eye. 

At present each cornea at its periphery has a row of dense 
opacities, about three millimeters in diameter, separated by a 
small portion of clear cornea from each other, encircling it 
entirely. The opacities look very much like the opacities left 
on the cornea at times after an episcleritis. The center of 
each cornea is clear, but the healing of each ulcer seems to 
have put some uneven tension on the cornea, and, as a con- 
sequence, in the left eye especially, even this clear portion of 
the cornea is uneven. This fact is made quite plain b}^ the 
distortion of the images of the mires on the ophthalmometer, 
also by the circles on Placido's disk. 

The patient has been wearing glasses for two years, but 
they do not relieve the pain in her eyes and head. 



IRREGULAR ASTIGMATISM 217 

Ophthalmometer. — Irregular astigmatism, and regular astig- 
matism against the rule, 3D., axis 135° + or 45° — right eye. 
Irregular astigmatism, and regular astigmatism with the rule, 
5 D., axis 75° + or 165° — left eye. 
Test cards and trial 



I^- ^' = M = f* W. + 2.75 D. cyl., 135°. 

L. V- = f ^ 1^ W. + 3.25 D. cyl., 75° - .75 D. cyl., 165°. 

Reads Jaeger No. 1 from 5 to 15 inches. 

Ophthalmoscope. —B.. 2 D. at 45° and M. 1 D. at 135° right 
eye ; H. 3 D. at 165° and M. 1 D. at 75° left eye. The fundus 
of each eye was somewhat hazy and indistinct, and the meas- 
urement with the ophthalmoscope doubtful. 

Second test : one day later a second test was made. 

Ophthalmometer. — Irregular astigmatism in both. Regular 
astigmatism against the rule, 2.75 D., axis 140° + or 50° — right 
eye; regular astigmatism with the rule, 4.50 D., axis 75° + or 
165° - left eye. 

Test cards and trial lenses. — 

I^' "^^ H • f^ - W- + 2 D. cyl., 140° - .75 D. cyl., 50°. 
L. V. f^ : 1^ W. 4- 3 D. cyl., 75° - .75 D. cyl., 165°. 

Two days later a third test was given, which corresponded 
with the second, and the glasses were ordered in cross-cylin- 
ders. These glasses were worn constantly, and proved very 
satisfactory. 

The patient was wearing, when she came under my care, 
+ 50 D. sphere right eye, and -1- 2 D. cyl., 75° left eye, which 
helped the right eye not in the least and the left e3^e but little. 
With the aid of the ophtlialmometer and three tests, without 
atropine, she was fitted with comfortable and much appre- 
ciated glasses. She continued under observation for about six 
months' time, and the glasses were still satisfactory at the 
end of that time. 



218 THE EEFRACTIOX OF THE EYE 

Case LXXXVIII. Regular astigmatism with the rule right 
eye ; Irregular^ astigmatism associated with a large amount of 
regular astigmatism with the rule of a mixed nature left eye; 
Asthenopia. — February 3, 1893, Katie B., aged sixteen years, 
in good general health, has been troubled with weak eyes ever 
since a child. She had ulcers on the left eye when a child, and 
has had calomel dusted into the eye for a long time, but with- 
out much benefit to vision or clearing up of the opacities. 

Ophthalmometer. — Astigmatism with the rule, ID., axis 
90° + or 180° — right eye. Irregular astigmatism, also regular 
astigmatism with the rule, 4.50 D., axis 90°+ or 180°— left 
eye. 

Test cards and trial lenses. — 

^' ^- = f^ • ff W. + .75 D. + .25 D. cyL, 90°. 

L. V. = 2V0 '- 1% ^^- + 1-50 D. cyl., 90° - 2 D. cyl., 180^ 

Reads Jaeger No. 1 from 4 to 14 inches. 

Ophthalmoscope. —YL. 1.50 D. right eye; M. 2 D. at 90° 
and H. 2 D. at 180° left eye. The fundus in the left eye is 
indistinct and the error of refraction difficult to estimate. 

A second test resulted in the patient accepting exactly the 
same glasses as at the first test, and they were ordered. The 
diffuse opacities on the cornea in the left eye prevented much 
improvement in the vision, even after the greater part of the 
astigmatism was corrected, but, as the patient accepted exactly 
the same glasses on two successive tests, they were ordered. 
These glasses gave relief from her painful vision for two 
months, since which time she has not been under observation. 

Case LXXXIX. Marked irregular astigmatism^ with a large 
amount of regular astigmatism with the rule right eye ; Regular 
astigmatism against the rule left eye ; Asthenopia only to a limited 
degree. — February 22, 1896, P. T. Q., aged twenty-six years, 
in first-class health, has always seen poorly, comes for a pair 
of glasses. When a child he had an ulcer on the right eye. 



IRREGULAR ASTIGMATISM 219 

He does not complain of much pain in the eyes or head, but 
chiefly of poor vision. 

Ophthalmometer, — Irregular astigmatism, also regular as- 
tigmatism against the rule, 5 D., axis 165° + or 75° — right 
eye ; regular astigmatism against the rule, 1 D., axis 180° + 
or 90° - left eye. 

Test cards and trial lenses. — 

R- V. = do : iV^ W. - 2 D. - 5 D. cyl., 75°. 
L. V. = ^% : II W. - 1.50 D. cyl., 90°. 

Reads Jaegar No. 1 from 5 to 12 inches. 

Ophthalmoscope. — M. 3D. at 75° and 8 D. at 165° right 
eye ; Em. at 90° and M. 2 D. at 180° left eye. A large 
opacity occupied the lower half of the right cornea, extending 
up to a level with the lower edge of the pupil. 

A second test corresponded with the hrst, and the glasses 
were ordered. They were worn with comfort, and with great 
improvement in vision. 

Case XC. Irregular astigmatism very slight., associated 
with mixed astigmatism of large amount against the rule left eye ; 
Ummetropia right eye. — June 3, 1896, C. J. S., aged twenty- 
seven years, in perfect general health, consulted me on account 
of poor vision in his left eye. Five years ago he had gonor- 
rhoeal ophthalmia in the left eye, with perforating ulcer of the 
cornea. There is a small dense opacity at the lower portion of 
the cornea, but with no synechia, however, between the iris and 
cornea, and the pupil is central, circular, and active. He was 
fitted to glasses shortly after his recovery from the ophthalmia, 
which have given satisfaction until the last two months. The 
left eye has pained him after doing close work of any kind for 
the last two months. 

Ophthalmometer. — Regular astigmatism with the rule, 
.50 D., axis 90° + or 180° — right eye ; slight irregular astio-- 



220 THE REFRACTIOX OF THE EYE 

matism, also regular astigmatism against the rule, 4 D., axis 
140° + or 50° - left eye. 

Test cards and trial lenses. — 

R. V. = -||^ — : not improved. 

L. V. = ^Oq - : 1^ - W. + 2 D. cyl., 140° - 1.50 D. cyl.,50°. 

Reads Jaeger No. 1 from 6 to 21 inches. 

Ophthalmoscope. — H. .50 D. right eye; H. 2 D. at 50° 
and M. 2 D. at 140° left eye. 

Two days later, a second test was made, and the patient 
accepted exactly the same glass as at the first test. Ordered a 
plain glass right, and + 2 D. cyl., 140° - 1.50 D. cyl., 50° 
left eye. The glasses gave him complete relief from pain in 
the eye. 

I kept the patient under observation for more than two 
years, and at the end of that time he continued to wear the 
same glass with comfort. 

The irregular astigmatism was but slight in this case, yet 
enough to be detected by the ophthalmometer, and this could 
be done especially when the arc was in the vertical meridian. 
The fact, however, of the cornea being perfectly clear at the 
point intersected by the visual line, allowed good vision when 
the regular part of the astigmatism was corrected. The 
amount of amblyopia that is usually present in such cases was 
not present here. I think this can be accounted for by the 
fact that this astigmatism was acquired, that is, it was pro- 
duced by a contraction of a scar on the lower half of the 
cornea. The perceptive part of the eye was not damaged by 
the ophthalmia, as proved by the fact that the eye had almost 
perfect vision when the astigmatism was corrected. 

Case XCI. Irregular astigmatism associated loith a large 
amount of regular astigmatism tvith the rule in each eye ; Anti- 
metropia; Trichiasis; Asthenopia; Relief with operation and 
glasses. — September 24, 1896, W, B. L., aged twenty-nine years, 



IRREGULAR ASTIGMATISM 221 

in good health, has been troubled with his eyes since fourteen 
years of age. This trouble began with inflammation of the 
lids, followed by ulcers on the eyes, and for the last four years 
he has had " wild hairs " on the left eyelids, which hairs he had 
pulled out from time to time. 

On account of the trichiasis and slight entropion of the left 
upper lid, an entropion operation was performed on this lid 
before glasses were fitted. Two weeks after the operation the 
first test was made. 

Ophthalmometer. — Astigmatism with the rule, 6 D., 75° + 
or 165° — , with irregular astigmatism right eye ; astigmatism 
with the rule, 6 D., 80° + or 170° — , with irregular astig- 
matism left eye. Although the irregular astigmatism was made 
quite manifest by the distortion of the images of the mires, 
and by the wavy outlines of the line dividing the mires, 
there was a large amount of regular astigmatism present which 
could be measured with reasonable accuracy. 

Test cards and trial lenses. — 

I^- ^- = 2'A • M W - 3.50 D. - 4.50 D. cyl., 170°. 
L. V. = JJL : 1^ W + 4.50 D. cyl., 80°. 

Reads Jaeger No. 1 at 8 inches. 

Ophthalmoscope. —M. 10 D. at 90° and 5 D. at 180° right 
eye ; Em. at 90° and H. 5 D. at 180° left eye. There are a 
few scattering fine opacities on the right cornea ; on the left 
€ornea, especially at the upper margin, the opacities are more 
numerous, giving a faint hazy view to the fundus. 

Four days later, a second test was made, when the patient 
accepted the same glasses as at the first test in the left eye, 
and the same cylinder in the right, but with a half diopter 
weaker sphere. Ordered : — 

- 4.50 D. cyl., 170° right eye ; 

+ 4.50 D. cyl., 80° left eye. 



222 THE REFRACTION OF THE EYE 

This patient was kept under observation for fifteen months^ 
and the glasses were at that time still worn with satisfaction 
and relief from his asthenopic symptoms. 

Considering the fact that this was a case of antimetropia, 
that a moderate degree of irregular astigmatism was present 
in each eye, together with a large amount of regular astig- 
matism, the result was gratifying. The axis of the cylinder 
in the right eye did not agree with the reading of the ophthal- 
mometer by 5°, and 1.50 D. of astigmatism had to be deducted 
from the reading of the instrument in each eye, instead of the 
usual .50 D. as is usually the case when the astigmatism is with 
the rule. 

Case XCII. Irregular astigmatism; Regular astigmatism; 
Blepharitis marginalis; Partial relief with glasses. — February 
4, 1896, Mrs. L. G. F., aged twenty-six years, in poor general 
health, has had weak eyes since a small child, she says follow- 
ing an attack of measles. She has never worn glasses. Two 
years ago she had recurrent ulcers on the left eye ; and in the 
last few months has had the same trouble again, and her family 
physician, Dr. J. T. Wheeler, referred her to me on that 
account. 

On the right eye, just below the center of the cornea on 
a level with the lower edge of the pupil, is a small dense 
opacity. On the left cornea near its center are four small 
facets ; and on the lower outer quadrant an oval-shaped opac- 
ity, about 3 mm. long and 2 mm. broad. The edges of the 
lids are red, and there are some scales on them. She has an 
herpetic eruption on the hands, and she says when the hands 
are bad the eyes are better, and vice versa. I may add that she 
is a very nervous woman. 

Ophthalmometer. — Irregular astigmatism slight, with regu- 
lar astigmatism with the rule, 3 D., axis 105°+ or 15°— right 
eye ; irregular astigmatism marked, with regular astigmatism 
with the rule, 3D., axis 105°+ or 15°— left eye. 



IRREGULAR ASTIGMATISM 223 

Test cards and trial lenses. — 

R- V. = jf^ : If W. - 6 D. - 1 D. cyl., 15°. 
L- V. = 2fo = M W. - 5 D. - 2 D. cyl., 15°. 

Reads Jaeger No. 1 at 6|^ inches. 

Ophthalmoscope. — M. 7 D. each. Slight posterior staphy- 
loma in each eye to the temporal side of the disk. 

A wash of boracic acid was given, also yellow oxide of mer- 
cury ointment (gr. i to 51) was ordered. After ten days' 
treatment a second test was given. 

Second test : the ophthalmometer gave the same reading as 
before. 

Test cards and trial 



R. V. = 2V0 : 1^ W. - 5 D. - 2 D. cyl., 15°. 

L. V. = ^to ^ I* W. - 5 D. - 2 D. cyl., 15°. 

Reads Jaeger No. 1 at 7 inches. 

These last glasses, with .50 D. deducted from the spherical 
portion, were ordered. They gave the patient much relief 
from the strained feeling in the eyes and made her much more 
comfortable. After wearing them for two years I saw her 
again. In the last month before the second visit to me, she had 
had a small ulcer on the left eye. This reduced the vision 
somewhat in that eye, but no glass could improve the vision 
more than the one she had on, so no change at all was made in 
the glasses. The right eye remained as when I first saw her. 
Her general condition was somewhat improved, but was still 
very poor. 

Case XCIII. Irregular astigmatism associated with com- 
pou7id myopic astigmatism against the rule left eye; Compound 
myopic astigmatism against the rule right eye ; Asthenopia ; lie- 
lief with glasses. — November 6, 1897, S. JM. B., aged sixteen 
years, in good general health, consults me on account of poor 



ftU 



224 THE KEFRACTION OF THE EYE 

vision and pain in the left eye. She had an ulcer on the left 
eye when eight years of age which perforated, and since then 
has seen poorly in that eye. She does not see the blackboard 
well at school. 

She has worn glasses (— .50 D. sphere) on each eye for the 
last six months, but with little improvement in vision. 

Ophthalmometer. — Astigmatism with the rule, .50 D., axis 
90° + or 180° — right eye ; irregular astigmatism, with regular 
astigmatism against the rule, 2.50 D., axis 30° + or 120° — left 
eye. 

Test cards and trial lenses. — 



R. V. = |i 


■■u- 


■ W. 


-1.25D. 


L. V. = -ii. 


:n 


w. 


-4 D. 



2 D. cyl., 120°. 

Reads Jaeger No. 1 from 4 to 15 inches. 

Ophthalmoscope. — M. 1 D. right eye ; M. 4 D. at 120° and 
6.50 D. at 30° left eye. There is an opacity on the left cornea 
about 3 mm. in diameter, with the lower pupilary margin of the 
iris incarcerated into it. This opacity is situated halfway be- 
tween the center of the cornea and its lower margin in the 
vertical meridian. The fundus in each eye is normal. 

Second test : three days later, a second test was made. 

Ophthalmometer. — Astigmatism with the rule, .25 D., axis 
90° + or 180° — right eye ; the same reading in the left eye as 
at the first test. 

Test cards and trial lenses. — 

I^-"^-= M =I^W. - .75 D.- .25 D. cyl., 90°. 
L. V. = Jq^o : f^ W. - 3.50 D. - 2 D. cyl., 120°. 

Reads Jaeger No. 1 from 4 to 15 inches. 

The ophthalmoscope gave the same result as at the first test. 

These last glasses were ordered to be worn constantly. 
They gave immediate relief and were worn for a little over a 
year with comfort, but at the end of that time, November 26, 



CONICAL CORNEA 225 

1898, she came again, complaining of some pain in the eyes, and 
also of burning and itching of the eyelids. After treating the 
eyelids for a week, I again tested the eyes with the following 
result : — 

Ophthalmometer. — Astigmatism with the rule, .25 D., axis 
90° + or 180° — right eye ; irregular astigmatism and regular 
astigmatism with the rule, 2.50 D., axis 45° + or 135° — left eye. 

Test cards and trial lenses. — 

^' ^- = M • I* W. - 1 D. ^ .50 D. cyl., 90°. 
L. V. = 2W • f^ W. - 3.50 D. - 1.50 D. cyl., 135°. 

Reads Jaeger No. 1 from 4 to 16 inches. 

Ophthalmoscope. — M. 1.50 D. right eye ; M. 4 D. at 135° and 
M. 6 D. at 45° left eye. Normal fundus in each eye. 

On a second test, the patient accepted exactly the same 
glasses, and they were ordered. For the two months that she 
has worn them they have given relief from the pain in the eyes. 

Conical Cornea 

In cases of conical cornea, there is always more or less irreg- 
ular astigmatism ; and, while the ophthalmometer is not capa- 
ble of measuring this astigmatism with exactness, either as to 
the amount or the axis, yet with it we are enabled to closely 
approximate them. Even in extreme cases, when the center of 
the cornea is so pointed, or occupied by an opacity, that it is 
no longer fit for visual purposes, by the help of the ophthalmo- 
meter and Placido's disk we are able to select the most suit- 
able and clearest portion of the cornea outside of the center, 
near or in the visual area, which is best for visual purposes. If 
this favorable spot is too far from the visual area, and not in 
front of the pupil, an iridectomy may be performed behind it, 
and thus an artificial pupil be made. Not only are Ave able to 
select this spot with the oplithalmometer, but, by its aid, we 
can measure the astigmatism here, — only approximately cor- 



226 THE REFRACTION OF THE EYE 

rect, of course, — and we are able often to improve the vision 
with cylinders in many of the cases. 

I am perfectly aware of the fact that the astigmatism is of 
such a high degree in many of these cases of conical cornea, as 
it is also many times after cataract extraction, that the ophthal- 
mometer, as now constructed, is only capable of giving the rel- 
ative difference of the dioptric power of the two chief meridians 
of the cornea, and not the absolute or exact measurements in 
such cases. Helmholtz,^ long ago, pointed out the fact that, in 
order to measure the curvature of the cornea in its various 
meridians, one can only use images which are considerably 
smaller than the radius of curvature of the cornea, — not 
larger than one-quarter of the size of the latter. He also 
shows that one should endeavor to accurately determine these 
images to the one-hundredth part of a millimeter if one wishes 
to calculate accurately the radius of the cornea to the one two- 
hundredth part of its size. 

Reid,2 in an article on the "Scope and Limits of Ophthal- 
mometry," says, "With Javal's instrument, with an image of 
3 mm., and with the portable ophthalmometer (Reid's), with an 
image of 2 mm., it is clear that from the spherical aberration 
the absolute size of the radius cannot be determined without 
reduction, as Leroy has done." And Reid also suggests that 
in very high degrees of astigmatism it would be better to have 
an image of only 1.50 mm. in diameter, especially when it 
comes to measuring the strongest curved meridian. 

In order to have such an image it would be necessary to 
have an extra prism for the instrument, which would cause a 
doubling of only 1.50 mm., that is, giving an image of 1.50 
mm. in diameter. Such a prism can be obtained from the 
manufacturers. 

For all ordinary cases, however, the instruments, as now 

1 Graefe's Arch. Oph. Vol. I, No. 2, p. 854. 

2 Annals of Ophthal., St. Louis, Vol. VI. p. 456. 



CONICAL CORN^EA 227 

constructed, are accurate enough. In the exceptional cases of 
very high degrees of astigmatism, as in conical cornea and 
some cases after cataract extraction, the difference in the cur- 
vature of the two chief meridians, as a rule, can be approxi- 
mated closely, as can also the position of these two chief 
meridians. 

The following case of conical cornea will serve to illustrate 
the points referred to. See, also, the chapter on Astigmatism 
after Cataract Extraction. 

Case XCIY. Conical cornea^ extreme in the right eye and 
marked in the left ; Irregular astigmatism ; No improvement with 
glasses in the rights but the vision was brought from ^^-^ to |-§- with 
glasses in the left eye. — December 7, 1898, Miss Nellie F., aged 
thirty-three years, general health is poor, being subject to sick 
headaches, especially severe at the menstrual periods. She had 
good sight until thirteen years of age, when she began to men- 
struate very profusely, losing great quantities of blood at each 
period, and the sight began to fail rapidly, particularly in the 
right eye. She became very anaemic, and the vision continued 
to grow worse for two years, after which time it appeared to re- 
main about as it is now. She had considerable pain in the eyes 
for the first two years. She cpnsulted an oculist at that time, 
and also another when twentjr-three years of age. Besides 
tonics, they prescribed a simple minus 5 D. spherical glass, 
which gave her ^^-^ vision in the left eye, but no improvement 
in the right. 

Ophthalmometer. — Astigmatism against the rule, about 4D., 
axis 165°— or 75° + , with irregular astigmation right eye ; 
astigmatism against the rule, 8D., axis 30° -f or 120°— left eye, 
with irregular astigmatism. 

■Test cards and trial lenses. — 

R. V. 2^0" : not improved. 

L V ~^- -sow _ 10 D cvl 120° 



228 THE REFRACTION OF THE EYE 

Reads Jaeger No. 1 from 4 to 10 inches with the left 
eye. 

Ophthalmoscope, — Shows an extreme degree of conical 
cornea right, and a marked degree left eye. The shadow 
crescent of conical cornea is beautifully shown in each. In 
the right eye the shadow was so pronounced as to suggest an 
opacity in the lens, but oblique illumination showed a perfectly 
clear lens, as well as a clear cornea. The ophthalmoscope also 
showed the lens to be perfectly clear when the pupil was 
dilated to permit of a thorough examination. The parallactic 
movement was very marked and nicely shown in the left 
fundus. The fundus in the right eye could be seen but in- 
distinctly with either the direct or indirect method ; the fundus 
in the left could be seen very well, but only parts of it at 
a time, the blood vessels and background changing with 
each movement of the eye or of the ophthalmoscope. There 
were no opacities in the vitreous, and the fundus appeared 
normal. 

Retinoscopy was totally useless in this case, and even the 
ophthalmoscope was of but small service in the estimation of 
the refraction. The subjective test with the clock-dial was 
altogether unsatisfactory. The ophthalmometer and the sub- 
jective tests with the test case 'and trial lenses were the only 
methods of value in giving the glasses. 

After several tests without a mydriatic and two or three 
with a mydriatic, in which all of the tests substantially agreed, 
I ordered for the right — 5 D. sphere (simply to balance the 
glass in the left eye), and for the left —10 D. cyh, 120°, in 
the form of a periscopic sphero-cylindric lens. Instead of 
giving a - 10 D. cyl., 120°, I ordered - 5 D. - 10 D. cyl., 
120° -f 5 D. That is, a + 5 sphere was ground on one side 
of the glass, and — 5 D. sphere and — 10 D. cyl., 120° were 
ground on the other side. In effect, this glass is the same 
as the - 10 D. cyl., 120°. 



CONICAL CORNEA 229 

These glasses were for the distance. For readmg, I pre- 
scribed in the right — 5 D. as for the distance ; and in the left 
eye + 3.50 D. cyl., 30° - 6.50 D. cyL, 120°, which magnified the 
print more than the distance glasses. With these she could 
read Jaeger No. 1 from four to eight inches better than with 
the distance glasses. But she could read the Jaeger No. 1 with 
her distance glasses, and with the advantage of holding the 
print a little farther from the eyes, though it was some smaller. 
I advised her to use the distance glasses as much as possible. 

For a description of periscopic and toric lenses, see the 
chapter on cataract glasses, where instead of giving a simple 
bi-convex lens or sphero-cylinder, a toric lens is often given 
with great advantage. 

In the present case, the first few days after the patient had 
her glasses they made her very dizzy, and she could not wear 
them in the street, but after a few days' trial, she was able to 
go on the street at will ; not only this, but she was able to- 
wear the one pair of glasses, the distance, both for the street 
and reading. Her headaches were made worse and the attacks 
more frequent for the first few weeks after putting on the 
glasses ; but her vision was so greatly improved that she per- 
sisted in the use of the glasses, and now, four months after, the 
headaches are much less frequent and less severe. In fact, I 
saw her within the week (April 7, 1899), and she tells me she 
has not had a single headache for the last month. Her general 
health also has improved. 

I not only measured this patient's cornea near the center 
(where the visual lines cut), but 15° above, below, in, and out. 
I also located the extreme tip of the cone in each eye, which 
was down and out, between 7° and 8° from the center of the 
cornea in each. 

The disk of Placido was of value in this case, and I give 
drawings of its reflections from the cornea in each eye. The 
marked flattening of the circles into irregular ovals is well 



230 



THE REFRACTIOX OF THE EYE 





15° TEMP^ 



shown, the ovals being more drawn out on the side away from 
the center of the cornea (see Figs. 91 and 92). 

The ophthalmometric readings in this case, as indicating 
the radius of curvature and the refractive power of the cornea 
in its two chief meridians at various points on its surface, 

were extremely inter- 
esting to me, and I give 
them below. 

Right eye : the ra- 
dius of curvature at 
the center (where the 
visual line intersects) in 
the meridian at 75° was 
4.38 mm., with a re- 
fractive power of 76 D. 
The meridian at 165® 
had a radius of only 
4.16 mm., with a re- 
fractive power of 80 D. 
Of course these re- 
sults are only approxi- 
mative, because the spherical aberration was marked and the 
irregular astigmatism so considerable that the images of the 
mires were made indistinct and irregular in outline ; not so 
indistinct, however, that approximate measurements could not 
be made.i For, while the irregular astigmatism was very con- 
siderable, it was not near so marked as after many cases of 
cataract extraction, or as in some cases where corneal opacities 
are present. 

1 It should be noted in this connection that a cornea with such a small radius 
of curvature cannot be measured with the ophthalmometer with the single 
movable mire, but only with the ophthalmometer with double movable mires. 
This is because with the single movable mire the object cannot be made large 
enough. For a description of the improvement of double movable mires, see 
Appendix. 



15° BELOW 

Fig. 91 (left eye). 



CONICAL CORNEA 



231 





The radius of curvature of the cornea changed greatly in 
the same meridian ; for instance, 15° below the center, in the 
meridian at 75°, the radius was 5.38 mm., that is, one whole 
millimeter longer than at the center, and with a refractive 
power of only 62 D. as against 76 D. at the center. The radius 
in the meridian at 165° 
was 4.76 mm., with a re- 
fractive power of 70 D. 

By these measure- 
ments it will be seen 
that while the radius of 
curvature has increased r(g)) 
in length in each me- i5°temp. 
ridian, relatively it in- 
creased more rapidly 
in the meridian at 75° 
than it did in the one 
at 165°, and, therefore, 
the astigmatism is much 
more marked 15° below 
the center of the cornea than at its center, in fact, just twice 
as great, being 8 D. 

Left eye : the left eye could be measured with greater 
precision than the right, because the cone was not nearly so 
marked as in the right. 

The radius of curvature at the center, in the meridian at 
120°, was 6.20 mm., with a refractive power of 50 D., while 
the radius in the meridian at 30° was 5.96 mm., with a refrac- 
tive power of 56 D. The mires of the ophthalmometer when 
turned from the second position, after being approximated, back 
to the primary position, overlapped eight steps, indicating an 
astigmatism of 8 D. against the rule. I may say that, in the 
right eye, a similar discrepancy in the difference in refractive 
power of tlie two chief meridians, as calculated from the radius 



15° BELOW 

Fig. 92 (right eye). 



232 THE REFRACTION OF THE EYE 

of curvature of these meridians, and as indicated by the over- 
lapping of the mires when turned from the second position 
back to the primary position, existed. But when the radius of 
curvature in one and the same medium changes so rapidly, as 
in conical cornea, such discrepancy may be expected. 

15° below the center (left), the ophthalmometer showed 
astigmatism against the rule, 5 D., 165° -|- or 75°—. The 
radius of curvature in meridian at 75° Avas 6.18 mm., with a 
refractive power of 54 D., while the meridian at 165° had a 
radius of 5.75 mm., with a refractive power of 58 D. 

15° to the temporal side of the center of the cornea, the 
ophthalmometer showed astigmatism against the rule, 6 D., 
axis 150° + or 60° — . The radius of curvature in the meridian 
at 60° was 6.96 mm., with a refractive power of 18 D., while 
the meridian at 150° had a radius of 6.18 mm., with a refractive 
power of 54 D. 

*15° above the center, the ophthalmometer showed astigma- 
tism against the rule, 11 D., axis 15° -h or 105° — . The radius 
of curvature in the meridian at 105° was 9.33 mm., with a 
refractive power of only 36 D., while the radius at 15° was 
7.11 mm., with a refractive power of 47 D. 

15° to the nasal side of . the center, the ophthalmometer 
showed astigmatism with the rule, 13 D., axis 75° + or 165° — . 
The radius at 75° was 7.11 mm., with a refractive power of 
47 D., while the meridian at 165° had a radius of 9.88 mm., 
with a refractive power of 34 D. 

Although both of the chief meridians of the left eye at the 
center (the point cut by the visual line) had a radius of curva- 
ture much shorter than the average (7.82 mm.), from which 
we would expect some myopia in addition to the astigmatism, 
nevertheless the patient would not accept any minus sphere, 
neither would she accept any plus glass, cylinder or sphere, 
either with or without the mydriatic. 

I tried the hyperbolic glasses of Raehlmann in this case, 



CONICAL CORNEA 233 

but could find none which improved the vision more than the 
ordinary glasses. 

For the benefit of those who have not had experience with 
the hyperbolic glasses of Raehlmann, I may say that they come 
in two series, designated '' A " and " B " respectively, and in 
each series there are eleven glasses. In the series designated 
'' A " the axis of the hyperbola is one-third of a millimeter, 
while in the series designated " B " the axis of the hyperbola is 
two millimeters. In order to fit such glasses, the best plan is 
to hand the patient each glass in turn in both series and let 
her move it in different positions in front of the eye until the 
part of a glass is found which gives the best vision, and this 
is marked on the glass and sent to the optician to be cut 
and centered to suit the spectacle frames. I have noticed 
that the vision is often much improved by holding the glass 
obliquely in front of the eye, just as after some cases of 
cataract extraction where there is a large amount of astigma- 
tism. These hyperbolic glasses may be obtained through any 
good optician. 1 

The hyperbolic glasses, besides being costly, are objectionable 
in another way : they narrow the field of vision, that is, the 
patient in order to see through them has to look directly 
through the optic axis ; for that reason they are not as suita-^ 
ble for the street as for near work. 

In some cases of conical cornea the vision is improved by 
means of the stenopaic slit and spherical glasses, but in this 
case it was not. While on this topic of conical cornea, it may 
be stated also that there is such a thing as a contact glass. 
That is, the glasses are ground in the shape of a meniscus, so 
that the posterior surface fits the front of the eyeball, somewhat 
after the nature of the artificial eje^ while the front surface 
is ground so as to correct the refractive error. The glasses, 
I believe, are made in Switzerland. I have known of but one 

1 Mr. Meyrowitz, of this city, keeps them in stock. 



234 THE REFRACTION OF THE EYE 

case in which they were tried, and in this case they had to be 
given up because of the irritation to the eye. They are worn, 
of course, just as an artificial eye would be. 

S. M. Burnett, of Washington, was the first observer in this 
country to make use of the ophthalmometer in measuring 
conical cornea ; for the report of his very interesting case, see 
Archives Oplithal., Vol. XIV, 1885, p. 169. 



CHAPTER IX 

STRABISMUS — INSUFFICIENCIES OF THE RECTI MUSCLES — 
AMBLYOPIA — ILLUSTRATIVE CASES 

The symptom, strabismus, convergent and divergent, is so 
intimately connected with and dependent upon errors of re- 
fraction, that a brief history of the discovery of this relation 
by Bonders, and its bearing upon this subject in general, is 
not out of place here. In fact, a knowledge of this relation, 
together with a knowledge of the intimate relation between 
convergence and accommodation, is of first importance, if a 
correct understanding of this subject is to be had. 

Not until 1864, when Bonders gave his epoch-making book 
— Accommodation and Refraction of the Eye — to the world, 
was the condition, or rather symptom, squinting, explained in 
a satisfactory way, and the wdiole subject placed on a scien- 
tific basis. All observers before Bonders left this subject in 
a hazy condition, even so great a man as Von Graefe failing to 
recognize the true cause of strabismus in most cases, to wit, 
errors of refraction. Von Graefe attributed the symptom of 
squinting chiefly to defective balance, or want of equilibrium 
of the external muscles of the eyes. He thought that accom- 
modation had something to do with it, but he never recognized 
the true connection, as cause and effect^ between hypermetropia 
and convergent strabismus, and myopia and divergent strabis- 
mus. And while, as Bonders says, many useful hints had been 
given in literature as to the cause of strabismus, yet no one had 
sought the cause of strabismus (convergent) in hypermetropia. 
And he further adds : " Indeed, this could scarcely be other- 
wise. It is only a fcAv years [1864 is the date of Bonders' book] 

235 



286 THE REFRACTIOX OF THE EYE 

since liypermetropia was properly understood ; and the forms 
wliicli are wholly or in great part latent were overlooked until 
I satisfied myself of their existence, and immediately began to 
perceive their relation to strabismus.""^ Again, in reference 
to divergent strabismus, he says : '* On the whole, little sat- 
isfaction is obtained by consulting the more recent copious 
literature on strabismus, with reference to its causes. Stra- 
bismus clivergens, in particular, is very imperfectly treated of. 
A distinction of the causes, according to the different forms, 
is not to be met with, and where the causes of strabismus in 
general are spoken of, the writers have evidently been filled 
with the idea of strabismus convergens.''^ 

Donders also quotes Yon Graefe to the effect that this 
observer believed that insutficiency of the internal recti mus- 
cles was the cause of divergent strabismtis. 

It was Bonders' thorough investigation of hypermetropia, 
myopia, and errors of refraction in general that revealed to 
him the close relation between accommodation and conver- 
gence, and gave to him the true relation of cause and effect 
that existed between hypermetropia and convergent strabismus, 
and myopia and divergent strabismus. 

The method or way in which hypermetropia prodtices con- 
vergent strabismus is explained as follows : In order that a 
patient with hypermetropia may see well for the distance, he 
must use a considerable amount of accommodative effort, and 
for near points even more, for, in such cases, the eyeball being 
too short, the rays focus behind the retina, and accommodative 
effort must be made to bring them up to it, if a clear image 
is to be obtained. As is now well known, accommodation and 
convergence are closely associated, and what calls one into 
pla}^ at the same time and within certain limits, calls the 
other, hence, when the patient has to use an excessive amount 

1 Donders. Accommodation and Eefraction of the Eye. p. 306. 

2 Loc. cit.. p. 415. 



CAUSES OF STRABISMUS 23T 

of accommodative effort, he at the same time calls into action 
the convergence. In doing this, however, sometimes the in- 
ternal recti overact, and one eye, usually the weaker one, 
shoots inward too far ; squints, if you please, leaving the 
better eye directed on the object. By suppressing the image 
in the weaker eye and squinting it inward too far, an exces- 
sive convergence is obtained, which, in turn, reacts on the 
accommodation in the good or fixing eye, and assists it by 
increasing its action in maintaining a clear image in. that eye. 
Thus single binocular vision for the two eyes is sacrificed in 
order that the patient can see clearly with one eye. 

Myopia produces divergent strabismus in the following 
manner : In looking at distant objects, or even at near 
objects, if the myopia is of moderate or large amount, myopes 
use no accommodative effort at all ; for the eye, being too long, 
is always too strongly refractive (the rays focussing in front of 
the retina), and, if accommodative effort is brought into use, it 
only makes matters worse. As a consequence, they relax their 
accommodation to the utmost, and, as convergence is controlled 
by the same nerve, — the third, — and acts in unison with 
accommodation w^ithin certain limits, the convergence in such 
cases is relaxed at the same time. By this continued relaxa- 
tion of the convergence, one eye — as a rule, the weaker- 
sighted one — turns too far out, that is, squints outward or 
diverges, while the better eye fixes the object. 

While Bonders maintained that hypermetropia was the 
cause of most cases of convergent strabismus, and myopia the 
cause of most cases of divergent strabismus, yet he did not lose 
sight of the contributory and auxiliary causes which cooper- 
ated in the production of strabismus. 

In Hypermetropia^ the causes are of a twofold nature : 
" (1) those whicli diminish the value of binocular vision ; 
(2) those which render the convergence easier." ^ Under the 

1 Loc. cit. 



238 THE REFRACTION OF THE EYE 

first class of causes lie includes : (1) difference in acuteness of 
vision of the two ejes, due to congenital defect in the retina, 
or to more marked refractive error in one eye than the other ; 
(2) spots on the cornea, or anything that interferes with the 
acuteness of vision. In the second class of causes he includes : 
(1) faulty structure or innervation of the external muscles of 
the eye ; (2) a large angle alpha^ especially when associated 
with a limited range of accommodation. 

To "paresis of accommodation" alone causing convergent 
strabismus, he gives but little weight, saying, " Diminished 
energy, or paresis of accommodation, by itself, is as little liable 
to produce strabismus as is the range of accommodation con- 
nected with the increase of years." On the other hand, Javal 
gives weight to this point, and thinks a " temporary paresis of 
accommodation " is a frequent cause of strabismus convergens, 
and explains it thus, "A patient whose accommodation sud- 
denly fails is obliged to make a great accommodative effort, 
which is facilitated by an excessive effort of convergence, that 
is to say, by an attack of strabismus." ^ 

In Myopia^ two sets of intiuences tend to produce divergent 
strabismus, which Bonders gave under the following headings : 
" (1) circumstances which promote movements outwards ; (2) 
such as deprive binocular vision of its value." 

Under the first set of influences he gives : (1) too strong 
external recti muscles ; (2) small or even negative angle alpha^ 
due to outward displacement of the visual lines ; (3) long and 
superficially placed eyeballs. 

Among the second class of causes he mentions : (1) unequal 
refraction of the two eyes ; (2) diminished vision in one eye. 

To the first set of causes should be added faulty innerva- 
tion or under-developed internal recti muscles. 

Buffon, Miiller, Rente, and others preceded Bonders in con- 
necting myopia and divergent strabismus ; but none of them 

1 Cited by Roosa, TJie Post- Graduate, December, 1897. 



CAUSES OF STRABISMUS 239 

had given the full significance of the relation between conver- 
gence and accommodation in these cases. 

I have given Bonders' views on strabismus somewhat at 
length, because, as I believe, they embrace the correct expla- 
nation of the method of production of the symptom, strabismus, 
and the true causes therefor. I may add, but little has been 
added to the knowledge of the subject, that is, as to its 
causes, other than of an auxiliary nature, since then. As to 
its treatment, operative and otherwise, much has been done. 

Roosa, in his recent Treatise on Diseases of the Eye^ gives 
the following conclusions in regard to the etiology of stra- 
bismus convergens, which, as will be seen, agree in the main 
with the conclusions of Donders. However, he lays more 
stress on a higher degree of hypermetropia or hypermetropic 
astigmatism in one eye than the other than did Donders ; 
" sufficient," as he says, " to produce what may be fairly termed 
an organic amblyopia," as an etiological factor in the produc- 
tion of squint. His conclusions are as follows : — 

" I. Convergent strabismus is generally associated with 
hypermetropic astigmatism or hypermetropia. 

" II. It is probably caused by congenital anisometropia 
(unequal refraction) in the majority of cases ; that is to say, 
by the inability to secure binocular single vision. 

" III. In a small contingent it is associated with equal 
vision in each eye. In such cases the patient fixes with either 
eye alternately. Why the strabismus then occurs is to me 
uncertain. If it were merely from hypermetropia, why do not 
nearly all people who are not myopic squint? 

" IV. Opacities of the cornea, or occlusion of the pupil of 
one eye, very much favor the occurrence of squint in eyes of 
any refraction. 

''V. If strabismus convergens be caused chiefly by ani- 
sometropia and refractive anomaly, it is not congenital, but 
it occurs at the age of from two to five years. 



240 THE REFRACTIOX OF THE EYE 

" VI. If congenital squint or organic disease of the retina 
exists, suspicion should be excited that it is caused by central 
disease." 

In regard to the query, in Conclusion III, as to the cause 
of the squint in hypermetropic eyes of equal acuteness of 
vision, I may say I believe it to be caused chiefly by a very 
large angle alijlia^ which is usually to be found in such cases. 
I may say also that I believe a very small or zero angle alplm 
accounts in a great measure for those anomalous cases of diver- 
gent strabismus sometimes present in h3^permetropia ; and that 
a very large positive angle alpha may account for the likewise 
anom^alous condition of convergent strabismus at times present 
in myopia. As the angle alpha, as an accessory cause of 
strabismus, will be discussed a little farther on, this bare 
statement is sufficient here. 

The most recent investigations of the anomalies of motility 
of the eye, in this country, are those by Duane, in a prize essay 
entitled : " A New Classification of the Motor Anomalies of 
the Eye, based upon Physiological Principles."^ 

In this essay he has made a very careful study of the 
motility of the eye, has measured the strength of the ocular 
muscles, tested their individual and associated movements, and 
as a result of his investigations has prepared a new classifica- 
tion of the motor anomalies of the eye, as he says, "based on 
physiological principles." I have not adopted the classifica- 
tion, but would refer my readers to the paper itself, which, 
I believe, is now to be had in book form. 

The conclusions that I have given above, as to the etiology 
of strabismus, I believe to be a fair expression of the mind of 
the profession of to-day. However, there were, and still are, 
some who believe that strabismus is due largely to the defects 
in the muscles themselves, while others believe it to be of cen- 
tral origin, or the result of imperfect innervation of the differ- 

1 Annals of Oph. and Otol., October, 1896, January, 1897, and April, 1897. 



V CAUSES OF STRABISMUS 241 

ent muscles of the eye. But Bonders' explanation, that in the 
fixed conditions of the eyeball was to be found the cause of 
most cases of strabismus, and that among the fixed conditions 
hypermetropia and myopia were the most potent factors, has 
never been overthrown. In fact, almost all observers since his 
first published views on this subject have concurred in his 
belief as to the great influence of hypermetropia and hyperme- 
tropic astigmatism, and myopia and myopic astigmatism in the 
production of strabismus, convergent and divergent respec- 
tively. It has been shown by many observers and numerous 
tables of statistics that hypermetropia or hypermetropic astig- 
matism is present in from 75 to 85 per cent of all cases of con- 
vergent strabismus (some observers giving as high as 98 per 
cent), while myopia or myopic astigmatism is present in from 
60 to 75 per cent of all cases of divergent strabismus. 

But it is concerning the accessory causes of strabismus that 
most dispute and discussion have arisen. Some authorities lay 
great stress on a "preexisting disturbance of muscular equi- 
librium." That is, to insufficiencies which finally terminate 
in actual strabismus. Other authorities have placed much 
emphasis on the amblyopia (congenital, or acquired from what- 
ever cause), usually present in the squinting eye, as the chief 
accessory cause in the production of the squint. For my own 
part, I believe that amblyopia plays a more important part as 
a predisposing cause of squint than do insufficiencies of the 
ocular muscles. 

Of course, all observers agree as to the influence of the 
long and superficially placed eyeball in myopia in the produc- 
tion of divergent strabismus. Here the axis of the eyeball, be- 
ing too long, naturally assumes the direction of the axis of the 
orbit, which, as is well known, is directed forward and outward. 

As to the " paresis of accommodation " causing strabismus 
convergens, some authorities give it little Aveight, Avhile 
others lay stress on the point. So far as my own observa- 



242 THE KEFRACTIOX OF THE EYE 

tions go, I must sav I have not observed a tendency to con- 
vergent squint in such cases. I beheve its absence in such 
cases is to be explained on the same ground upon which 
Donders explained the absence of convergent strabismus, as 
a rule, in verj' high degrees of hypermetropia. He saj's ; 
" In such cases the power of accommodation is, even under 
abnormally increased convergence, not sulhcient to produce 
accurate images, and such hypermetropics are thus led rather 
to the practice of forming correct ideas from imperfect retinal 
images than of, by a maximum of tension, improving the ret- 
inal images as much as possible." ^ I have had under my care 
for the last four months a young girl, aged thirteen years, with 
paresis of accommodation from no apparent cause, unless an 
attack of diphtheria four years previously, which affected the 
voice for a short time after, but not the vision, can be given as 
a cause. This patient has no tendency whatever to squint. She 
has a hypermetropia 2D., vision |-§-, which is brought up to 
1^1" with + .75 D. sphere, but she cannot read Jaeger Xo. 1 
closer than eight inches with her distance glasses on. Her 
mother brought her for examination because she held the 
print too far from her when reading, " as far as an old person," 
she said. The patient had no asthenopia whatever, was in 
perfect health, and had always been, except for the attack of 
diphtheria already spoken of. 

In several other cases of temporary paresis of accommoda- 
tion which have come under my observation, I have not noticed 
any tendency to convergent strabismus. But, as I said above, 
these few cases I have seen are not enough to justify me in 
drawing positive conclusions therefrom. 

The Axgle Alpha 

The angle alpha as an accessory cause of strabismus is of 
more importance than has, as a rule, been accorded it. The 

1 Zoc. c?^., p. 301. 



THE ANGLE ALPHA 



243 




angle alpha^ that is, the angle between the visual line (^0, 

Fig. 93) and the long axis of the cornea QCD^ Fig. 93) in the 

horizontal plane, has considerable influence 

in the production of strabismus, according 

to Bonders' and Hamer's investigations. 

As I wish to convey a clear idea, to the 

beginner especially, of the influence of the 

angle alpha as an etiological factor in the 

production of strabismus, I shall give some 

diagrams to help make clear the text on the 

subject. 

The figure produced to show the angle 
^Ipha is very diagrammatic. It represents 
the right eye as seen from above. XF", the 
optic axis, is the line joining the center of 
the cornea and the posterior pole of the eye. 
CD is the longest axis of the corneal ellip- 
soid. In the figure, the apex (C) of the 
corneal ellipsoid is represented as being far 
to the temporal side of the center of the 
cornea, the spot on the cornea cut by the 
optic axis, XY, As a matter of fact, these 
points almost coincide, and are so treated in 
actual practice. 

This being so, the long axis (CD) of the 
corneal ellipsoid and the optic axis (XF') 
would coincide, and they, also, are considered as one and the 
same in actual practice. ^ 

The angle alplia^ OKC^ is called positive^ or plus, when the 



Fig. 93. — Angle alpha 
(after Roosa). XT, 
optic axis ; H, prin- 
cipal points com- 
bined ; K, nodal 
points combined ; 
M, center of mo- 
tion; FO, line of 
vision ; MO, line 
of fixation ; CDy 
greater axis of 
corneal ellipsoid ; 
OEC, angle alpha 
(a) ; OMX, angle 
gamma (7). 



1 And, when they are so considered, the angle gamma, formed between 
the line of fixation, 031, and the optic axis, XY, varies, that is, increases and 
diminishes, in exact proportion with the angle alpha. Moreover, they become 
nearer equal the farther the object of fixation is removed from the eyes, and^ 
Tsvhen the object is at twenty feet or more, they become equal. 



244 



THE REFRACTIOX OF THE EYE 




A' ? 



Fig. 94. — Positive an- 
gle alpha of twelve 
degrees, right eye. 



front portion of the long axis of the corneal ellipsoid falls to 

the outer or temporal side of the visual line (Fig. 94) ; and 

this is the case in most eyes. 

It is said to be negative^ or minus, when the 
front portion of the long axis of the corneal 
ellipsoid falls to the inner or nasal side of the 
visual line (Fig. 95). .This is comparatively 
rare, but sometimes occurs in myopia. When 
the visual line and the long axis of the corneal 
ellipsoid coincide, it is evident that there can 
be no angle alpha at all ; then it is said to be 
nil. 

Now, in the first place, let us see what 
determines the character and the size of the 
angle alpha; and, in the second place, how 
the angle alpha influen-ces the eye to squint. 
A. The character of the angle alpha is determined by : — 
1. The position of the yellow spot^ or macula lutea^ in refer- 
ence to the posterior portion of the optic axis of the eye, that 
is, the posterior pole of the eye. It should 
be remembered that the optic axis and long 
axis of the corneal ellipsoid are regarded as 
one in practice, as represented in the two last 
figures. As long as the macula is situated to 
the outer or temporal side of the posterior 
pole of the eye, the angle alpha must be posi- 
tive ; for the visual line, FO (Fig. 93), must 
necessarily cut the cornea to the inner or 
nasal side of the optic axis, XT. Further- 
more, the further the macula is situated toward 
the temporal side of the posterior pole of the 
eye, the larger will the positive angle alp)ha 
be. If the macula lutea and the posterior pole of the eye 
are at the same spot, then the visual line and optic axis must 




F A 
Fig. 95. — Negative 
angle alpha of six 
degrees, right eye. 



THE a:n^gle alpha 



245 



coincide ; and there is no angle alpha^ or it is nil. If the 
macula lies to the inner or nasal side of the posterior pole, 
the visual line, FO (Fig. 95), must cut the cornea to the outer 
or temporal side of the optic axis, and the angle alpha becomes 





Figs. 96, 97, and 98. — Fig. 96, emmetropic eye; Fig. 97, myopic eye; Fig. 98, hy- 
permetropic eye. /, nasal side ; E, temporal side ; n, optic nerve ; ga, optic axis ; 
ll\ visual line ; d, center of motion ; K, nodal point. (After Bonders.) 

negative ; and the farther inward from the posterior pole of 
the eye the macula is situated, the larger the negative angle 
alpha will be. 

2. The length of the eyeball itself influences the size of the 
angle alpha. 

In emmetropia, the angle alpha is positive, and averages 
5°; in hypermetropia, it is positive, and averages 7.3° in non- 
squinting eyes ; while, in myopia, it 
is, as a rule, positive, but may be nil 
or negative, and averages a little less 
than 2°. These are the figures given 
by Bonders ; and this author explains 
the influence of the length of the eye- 
ball on the size of the angle alpha^ 
as follows : — 

" The distance, kg (Fig. 98), from the nodal point to the 
retina is to be taken into account. • It is evident that, if in the 
hypermetropic eye, wdiere this distance is particularly short, 
the yellow spot I is only at the ordinary distance from i^ (a 




246 



THE REFRACTIOX OF THE EYE 



point of the prolonged axis of the cornea), the angle ali^ha^ 
under which IV and ga intersect one another in ^, becomes 
greater. In this, therefore, really lies in part the cause of 
the greater value of alpha in hypermetropic eyes ; but, for the 
most part, this greater value must still be explained by the 
more external position of the yellow spot. 

" This position is connected with the arrested development, 
especially of the external portion of the hypermetropic eye."^ 
A glance at Fig. 97 shows the influence of myopia to diminish 
the size of the angle alpha^ by reason of its longer optic axis. 
B. Hoiv does the angle alpha influence the eye to squint? 
It is apparent, if the angle alpha is large, as it often is in 
high degrees of hypermetropia, that the long axes of the cor- 

nese (and the summits of the 
corneae) will be directed in a di- 
vergent direction when the vis- 
ual lines are parallel (Fig. 99). 
If this angle amounts to as 
much as 6° in a normal eye with 
a corneal radius of curvature of 
eight millimeters (a little above 
the average), the linear distance 
on the cornea, from the visual 
line to the optic axis (summit 
of the cornea), would be .9 mil- 
limeter, or, practically, one mil- 
limeter. With an angle alp)ha 
of 12°, as is sometimes found in 
hypermetropia of high degree, 
this distance would be nearly two whole millimeters. There- 
fore, with the visual lines of such eyes directed straight ahead 
and parallel, the summit of each cornea would diverge two mil- 
limeters, and the patient would appear to squint outward, 

1 Loc. cit, p. 249. 




/ 

I 




Fig. 99. — Showing an apparent diver- 
gent squint in hypermetropia of 
high degree, with a large angle 
alpha (positive). 



THE ANGLE ALPHA 247 

although single binocular vision was present. This apparent 
divergent squint is the so-called strabismus incongruus of Mid- 
ler, or the apparent squint of later writers. This apparent 
squint appears to be divergent in hypermetropia, and conver- 
gent in myopia. I have seen, more than once, after tenotomy 
for convergent squint in hypermetropia, apparent divergent 
strabismus occur ; and, before the screen test was tried, an 
overeffect from the operation was thought to be present. 
However, with the screen test, both eyes remained fixed when 
covered and uncovered, showing the visual lines to be parallel 
and fixed on the object. Again, I have seen cases, and have 
congratulated myself, in fact, on the beautiful result obtained 
after tenotomy for convergent squint, where the eyes were 
apparently straight and directed to the same object ; but, on 
the screen test being applied, first one eye and then the other 
turned outward, showing conclusively that the visual lines 
still converged and that the patient did not use the eyes 
together. 

Incidentally, I may say here, that this screen test is a sim- 
ple and easy way to decide between a true and a false or appar- 
ent strabismus. It consists simply in covering first one eye 
and then the other with a card, having the patient look at a 
distant light, preferably a candle, with the uncovered eye. If 
the eye that is covered changes position when uncovered (the 
card being placed in front of the other eye), it is a true squint, 
and shows that the visual lines of the two eyes are not directed 
to the same point. If the eye turns outward on being uncov- 
ered, it shows a convergent squint to be present, because while 
behind the card or screen it turned inward, while the uncov- 
ered eye fixed the object. On the other hand, if the eye turns 
inward on being uncovered, it shows a divergent squint to be 
present, because, while the other eye fixed the object, its visual 
line diverged, and only turned inward when uncovered and the 
opposite eye was covered. The same test may be made by 



248 THE REFRACTION OF THE EYE 

having the patient look at a near object, as the finger, or a 
pencil. 

The large angle alplia^ sometimes present in high degrees 
of hypermetropia, and giving rise to an apparent divergent 
strabismus, may lead to a true convergent strabismus, in the 
following manner : — 

Such eyes, in order to see binocularly and singly for the 
distance, have to direct their visual lines parallelly. But in 
doing this they have actually to diverge the centers of the 
corneee ; to do which the external recti may not be quite 
strong enough, especially since these patients have to exercise 
accommodation to see well even for the distance. This act of 
accommodation in itself stimulates convergence to a certain 
extent, which latter force would actually oppose the outward 
movement of the eye. If, therefore, these eyes have to make 
an effort, on account of a wide angle alpha^ to keep straight, 
that is, their visual lines parallel and directed to the same 
object in the distance, when they come to view near objects 
the tendency of the visual lines to unduly converge will be 
greater still, and the relative insufficiency of the external recti 
muscles for the distance may be converted into a true conver- 
gent strabismus for the near point. Bonders and Hamer were 
the first to investigate this point, and to bring statistics to 
bear showing the influence of a large positive angle alpha in 
producing convergent strabismus. These observers measured 
the angle alpha in a number of cases of hj'permetropia with 
convergent strabismus, and the same angle in a number of 
cases of hypermetropia of about the same degree as those 
which squinted, and found that the angle alpha averaged in 
size a little more than one degree larger in the squinting cases 
than in the non-squinting ones. 

Donders says: "The result therefore is, that, with equal 
degrees of hypermetropia, high values of alpha especially pre- 
dispose to strabismus convergens. To this I attach more im- 



THE a:n^gle alpha 



249 



portance, because it in general proves, that the greater angle 
alpha^ proper to hypermetropia, is not indifferent in its bearing 
on the connection between hypermetropia and strabismus."^ 

My own experience has led me to the same conclusion as 
that formed by Bonders, in regard to the influence of a large 
angle alpha as an accessory cause in producing convergent 
strabismus ; not only that, but I believe many of the anoma- 
lous cases of divergent squint in hypermetropia are to be ex- 
plained by a very small positive angle alpha^ or even with the 
angle nil, rather than by any muscle defect, either of insertion 
or structure, or imperfect innervation. My own observations 
on this point, and the cases reported farther on in this chapter, 
have led me to this conclusion. 

On the same ground of reasoning, the anomalous cases 
of convergent strabismus in myopia are to be accounted for 
most of the time, I believe, by the presence of a large positive 
angle alpha. 

A large negative angle alpha 
has the same tendency to pro- 
duce a divergent strabismus in 
high degrees of myopia that 
the positive angle alpha has in 
causing convergent strabismus 
in hypermetropia, except that 
it works in a reverse order. 

In such cases, in order to 
secure single binocular vision 
and to have the visual lines di- 
rected parallelly, the centers or Fig. lOO. — Showing the iuriueuoe of a 
.. « ,, , , large neo-ative aiui"le(/('p/n/ in produo- 

summits of the COrnese must be ^^^ ^^ .^^^.^^^^, eonvergenr sqnint. 

directed inward. Now in high 

degrees of myopia it is hard to turn the front of the eye inward 

on account of the long eyeball incident to such cases ; for the 

liocc/^., p. 301. 





250 THE REFRACTION OF THE EYE 

optic axes of these eyes have a tendency to coincide with the 
axes of the orbits, which latter have an outward direction. If 
it is difficult, therefore, for these eyes to turn the centers of the 
cornese relatively too far inward in order to have their visual 
lines parallel for distant objects, is it not much more difficult 
for them, with a wide angle alijlia^ to turn the eyes still farther 
inward in order to fix near objects with both eyes at the same 
time ? In fact, the wider the negative angle alpha^ the more 
difficult it is for the eyes to fix with both eyes at once, hence 
the direct influence it exerts in producing a true divergent 
squint, though it gives the semblance to the eyes of convergent 
strabismus at times. 

Such is the influence of the angle aljjlia^ positive and 
negative, in causing the eyes to squint. I have considered it 
somewhat at length, in order that the beginner might under- 
stand it, both as to the influence refractive errors have in the 
production of the angle alpha itself, making it positive or 
negative, and smaller or greater, as the case may be ; and the 
secondary influence the angle has in causing a true squint. 
Furthermore, it will teach him to observe between true and 
apparent or false squint. 

But it is not merely to show the influence of the angle alpha 
in the production of squint that I have gone rather fully into 
its exposition here, but also to show how the angle alpha may 
influence the reading of the ophthalmometer and the fitting 
of glasses. In an article in the New Yoi^k Medical Journal^ 
February, 1895, I have explained this influence. 

Those who are only fairly well acquainted vtdth the use of 
the ophthalmometer are aware of the fact that the whole of the 
cornea is not measured in an ordinary examination, but only 
a very small portion of it — a space of only 2 J to 3 millimeters 
in diameter. Furthermore, the center of this space does not 
coincide with the center of the cornea, except when the visual 

1 See also Appendix of this book. 



THE ANGLE ALPHA 251 

line coincides with the long axis of the cornea,^ but with that 
point on the cornea intersected by the visual line, which point 
is usually a little to the nasal side of the center of the cornea 
(2° to 5°), and, as a rule, on a horizontal line with it. How- 
ever, on rare occasions this point is on the temporal side of the 
center of the cornea, that is, when there is a negative angle 
alpha. 

When this angle is large, especially when there is a high 
degree of astigmatism, and associated with a large amount of 
hypermetropia or myopia, the readings of the ophthalmometer 
do not correspond so closely with the subjective tests as in the 
cases with lower amounts of astigmatism and with a small or 
average angle alpha. For example, in an eye with a radius 
of curvature of 8 mm., an angle alpha of 6° is 0.9 mm., or prac- 
tically 1 mm., and with angle alpha of 12° it would, of course, 
be 2 mm. (see Fig. 94). In such case, therefore, the point on 
the cornea measured by the ophthalmometer would be 2 mm. 
distant from the center of the cornea. Now the two chief radii 
of curvature at this point may be considerably different from 
the radii of curvature at the apex or center of the cornea. To 
simplify matters, we will assume that the radius of curvature, 
changes in but one of the chief meridians, that of the vertical, 
while it remains unchanged in the horizontal. 

Let the radius of curvature of the horizontal meridian at 
the center of the cornea be 8 mm., and that of the vertical 
meridian 7.61 mm. According to Javal's formula, 

D = 1000i^^— ^, 

T 

the astigmatism at the center of the cornea in such a case is 
2 D. Say, however,'at a distance of 2 mm. from the center of 
the cornea the radius of curvature of the vertical meridian 
becomes slightly shorter, changing from 7.61 to 7.81 mm. 

1 The long- axis of the cornea and the optic axis are considered as one and 
the same in practice. 



252 THE REFRACTION OF THE EYE 

in length, while the radius of curvature of tlie horizontal 
meridian remains the same as at the center of the cornea. 
According to the formula given above, the astigmatism at this 
point would be 4 D. The difference in the amount of the 
astigmatism at the two points would be clearly two whole diop- 
ters. Of course, this is a much exaggerated case, but it serves 
to illustrate how a large angle alpha may affect the readings of 
the ophthalmometer ; and how the astigmatism at the center of 
the cornea may vary from that at the point on the cornea 
intersected by the visual line. 

As to the mooted question of the amblyopia which is 
usually present in strabismus cases, whether tliis amblyopia 
is congenital and causes the squint, or the squint causes the 
amblyopia from non-use of the eye (^amblyopia ex anopsia^ ^ I 
shall have little to say, not having any new evidence to offer 
for either side. 

Many authorities believe that the amblyopia present in 
most cases of strabismus is usually congenital, that is, organic^ 
due to disease, and is the chief cause of the squint ; but that it 
is in a few cases acquired, functional^ and is brought about in 
such cases by the non-use of the squinting eye. The mere 
fact, however, that the great majority of squints (convergent) 
develop between the ages of two and seven years, makes it 
quite evident that on account of the youth of the patient, it is 
almost impossible to decide if the patient has amblyopia before 
squinting, even if tests were attempted. Those holding this 
view, as they cannot depend on such examinations to decide 
the point, must judge by the result of the operation, the cor- 
rection of the error of refraction and enforced use of the weak 
eye, to determine if the amblyopia is organic or functional. 
If organic, they say the amblyopia is not improved, while, if 
functional, it may be. And the fact, well established by 
experience, that the vision in the squinting eye, in the 
great majority of cases, is not and cannot by any means 



AMBLYOPIA m STRABISMUS 253 

whatever and however long persisted in be improved but 
very little, seems to lend weight to the contention that the 
amblyopia in nearly all these cases is organic and not func- 
tional. For, if not organic, they ask, why is not the vision 
improved when the eye is put in condition for seeing? 
Eyes with cataracts on them for years see after the cataracts 
are removed. Why is there not amblyopia in these cases 
from non-use, if non-use can cause an amblyopia, incapable of 
but slight or no improvement ? ^ 

Javal, of Paris, has, by the use of the stereoscope, by the 
enforced use of the weak eye to the exclusion of the good one 
for months at a time, etc., been able to secure improvement in 
vision in some of these apparently organic cases. But the 
majority of observers do not make such strenuous efforts, or 
persist in them for as long, as does Javal. After the im- 
provement obtained in the first few weeks, the vision is 
rarely further improved ; and, even though by the use of the 
stereoscope, and so forth, binocular single vision is restored, 
unless continued practice of the stereoscope is persisted in, this 
is lost again in many cases. Of course, where we have an 
intelligent patient, with the inclination and the leisure to keep 
up these exercises, it is entirely justifiable and should be en- 
couraged. 

Personally, I am of the opinion that the amblyopia in stra- 
bismus cases is usually functional, and due to the squint, 
though at one time I held the opposite view. That strabismus 
may cause, or, at least, be coincident with, amblyopia, there can 
be no doubt, as a few well-authenticated cases show. 

Dr. Walter B. Johnson, of Paterson, N. J., has reported 
the most remarkable case of this kind, as follows : — 

1 Fuchs claims that the non-use of a cataractous eye does not make it 
amblyopic, simply because the retina is developed and practiced before the 
cataract (senile) is formed ; but that in congenital cataract and squint cases the 
retina in the affected eye is often incompletely developed, hence amblyopia. 



254 THE REFRACTIOX OF THE EYE 

T. McK., aged nineteen, June, 1887, file forger, has been 
cross-eyed since three years of age, and states that during his 
recollection he had been unable with the left, squinting eye, to 
discern any object and define its character. He constantly 
fixes with the right eye.^ 

R. V. = ll". L. V. = fingers at 6 inches. Fundus normal 
in each. June 13, the right eye was injured so badly with a 
file that it was enucleated the same day. June 18, L. V. = 
fingers 3 inches. Under continued practice with test letters 
and reading cards, by July 1, L. V . = |4, and reads Jaeger Xo. 
1 at 12 inches. The false fixation which he had was overcome. 
Three years later. V. = ^^. 

'• The peculiarities in the case." Dr. Johnson says. '' are the 
length of time the amblyopia had existed (sixteen years), the 
return of perfect vision, and the shortness of time required for 
the vision to become normal." 

A second remarkable case of this nature is reported by Dr. 
St. John Roosa. 

Roosa's patient was a child aged seven years, from a squint- 
ing family, " who had no squint at time of examination, but 
was said to squint at times. R. and L. V. = |-J H. 5 D. She 
accepted and wore + 1: D. In four years after, this child 
came with a fixed squint, by preference in the right eye, and 
the vision in that eye was reduced to -^-^ : while the left, the 
non-squinting eye, remained at |-J. The examinations, first 
and last, were made with great exactness, by competent men^ 
— the late Dr. Edward T. Ely and my present associate. Dr. 
J. B. Emerson, — and I have no doubt of the truth of the 
observation. I advised an operation, but the case disappeared 
before I had the opportunity of making the crucial test of par- 
alyzing the accommodation, and securing the best vision pos- 
sible with glasses under such paralysis."^ 

1 Trans. Amer. Oj>h. Soc. July. 18P3, Vol. VI, p. 551. 

2 Treatise on Diseases of the Eye. p. 54y. 



INSUFFICIENCIES OF THE OCULAR MUSCLES 255 

' I may say, Roosa formerly held to the view that the ambly- 
opia was congenital, but does so no longer. 

Samuel D. Risley, of Philadelphia, reports a case of alter- 
nating amblyopia occurring in alternating convergent squint, 
with recovery in each eye. He also reports two other cases 
of amblyopia that became greatly improved. Harlan, Knapp, 
Holt, Javal, are others who have reported such cases. 

Certainly these cases furnish positive evidence, and are not 
evidence of the negative nature, which the congenital cases 
must necessarily be. For this reason they are very convincing.^ 

Insufficiencies of the Ocular Muscles 

Before proceeding to give illustrative cases of strabismus, I 
wish to speak briefly of insufficiencies of the ocular muscles, 
especially in their relation to refractive errors. 

To Graefe belongs the honor of clearly distinguishing 
between muscular insufficiency and strabismus, and we are 
deeply indebted to him for his classical investigations in this 
field of work. Although some of his methods of testing the 
muscles were at fault, and have since been given up, yet his 
investigations put the subject on a scientific basis, and pointed 
the way for later investigators. 

We are also greatly indebted to Alfred Graefe for his con- 
tributions on the subject of strabismus and muscular insuffi- 
ciencies. It was he who emphasized the fact that before 
testing for insufficiencies of the ocular muscles we should first 
correct any refractive errors that might be, and often are, 
present in such cases, a point, by the way, of prime impor- 
tance. Other distinguished investigators have added to the 
subject, but the name of the two Graefes stands out conspicu- 
ously. 

1 For a very valuable paper on this subject, see Annals of Ophthalmolocfi/ 
and Otology, April, 1895, "An Argument for xVmblyopia ex Anopsia in Con- 
vergent Strabismus," by W. Franklin Coleman. 



256 THE REFRACTIOX OF THE EYE 

The insufficiency of a muscle may rightly be called a latent 
strabismus. It may be of the slightest amount or very marked, 
and may develop into a true or manifest squint, especiall}' when 
associated with large errors of refraction, or when prisms are 
prescribed and gradually increased in strength, thereby stimu- 
lating the stronger, antagonistic muscle to even greater exertion. 

Muscular insufficiency of large, or even of moderate, degree, 
that is, of amount sufficient to give rise to asthenopic symp- 
toms or to call for operative interference, not associated with 
troublesome refractive error or a general debility, is so rare as 
hardly to call for consideration at all, except for the satisfac- 
tion obtained in making a complete examination in every case. 
As for the insufficiencies that are associated with refractive 
errors, we know that these, as a rule, are relieved by simply 
correcting the refractive error. In the few cases that are not 
relieved by glasses alone, tonics, rest, and outdoor exercise, by 
those who can take it, will generally accomplish the desired 
result. 

In the very limited number of cases that are not relieved 
by the above methods, and where the muscular insufficiency is 
so great as at times to cause diplopia and great annoyance, oper- 
ative interference is called for in the form of a tenotomy — a 
complete tenotomy, and not the so-called graduated tenotomy. 
However, the cases that call for operative procedure are rare, 
as nearly every case of muscular insufficiency can be relieved 
with glasses, rest, outdoor exercise, and tonics. And I agree 
with Roosa when he says, " So long as there is no deformity, 
so long as the patient has no double vision, and can see to read 
well with the eyes, any operative interference, in m}' judgment, 
is utterly unwise, and founded on a false conception of the 
true condition of things." ^ In other words, I believe that no 
operation is justifiable in these cases until the insufficiency 
(which is a latent squint) develops into an actual manifest 

i The Fast Graduate, December, 1897, p. 725. 



INSUFFICIENCIES OF THE OCULAR MUSCLES 257 

squint, periodic in nature, but, nevertheless, a true squint. 
Operative measures, even then, should not be undertaken, 
except in adults (sixteen years of age or over), and until all 
other means have failed. 

There are a few cases of muscular insufficiency that are not 
relieved by any procedure whatever — glasses, tonics, rest, op- 
erations, or what not. These cases, Knapp says,^ are benefited 
by the effects of age. He said he had been told this by Graefe, 
when working in his clinic, and that it had been borne out in 
his experience. In some way, increasing age seemed to har- 
monize the maladjustment between convergence and accommo- 
dation ; which maladjustment, probably, was at the bottom of 
most of these cases. He thought the idea advanced by Dr. 
S. M. Payne, in one of his papers on this subject, of correcting 
the refractive error almost fully in those cases with excessive 
convergence, to be the correct one, and one giving more re- 
lief than any other procedure. 

Perhaps it is not out of place here to give the meaning of 
the terms adduction, abduction, sursumduction ; the methods 
of testing for insufficiencies of the ocular muscles, and what 
may be considered an insufficiency of action in a muscle as 
measured by prisms, the tropometer (Stevens), or otherwise ; 
and the ratio or relative strength of a muscle as compared to 
the other muscles. 

Adduction means, literally, to turn to or toward; and, as 
regards the median plane of the head, this would be inward 
turning of the eyes. It is accomplished chiefly by the inter- 
nal recti muscles, assisted by the superior and inferior recti 
muscles. 

Abduction means, literally, to turn outward. It is accom- 
plished chiefly by the external recti muscles, assisted by the 
superior and inferior oblique muscles. 

1 In discussion of a paper read by Dr. Noyes, at the Oph. Sec, Academy 
Med., January 16, 1899. 



258 THE REFRACTIOX OF THE EYE 

Sursumduction means, literally, to turn upward. It is ac- 
complished chiefly by the superior recti muscles, but is assisted 
by the inferior oblique muscles. 

Deorsumduetion means, literally, to turn downward. It is 
accomplished chiefly by the inferior recti muscles, but is 
assisted by the superior oblique muscles. 

Methods of measuring the ocular muscles. — In my office I 
measure the strength of the different ocular muscles, that is, 
measure the adduction, abduction, sursumduction, with prisms, 
in the simplest way possible, as follows : With both eyes open, 
and directed to a candle flame twenty feet distant, I begin 
with the lowest prism in the case, with the edge or apex of the 
prism over the muscle to be tested, and gradually increase the 
strength of the prisms until the patient sees double. For 
example, to get the adduction, that is, to measure the strength 
of the internal recti, I begin with a prism 1°, apex inward, and 
gradually increase its strength till the patient sees double, or 
can no longer bring the images together after they are doubled ; 
for it often happens that a patient will see double when a 
prism of certain power is first placed in front of the eye, espe- 
cially in measuring for adduction ; but, after a second or two, 
the images will come together. Another prism, a little 
stronger, is then to be tried, till a prism is reached that the 
patient cannot fuse the images with after they have once been 
separated. Say the jDatient overcomes a 14° prism, apex in, 
but that a 15° prism makes him see double. His adduction 
(prism convergence) is 14°. 

To measure abduction, place apex of the prism outward 
over the external rectus muscle, and gradually increase its 
strength, till the patient can no longer see the candle single. 
For example, say he can overcome a 7° prism, but not 8°. His 
abduction is 7°. 

To measure sursumduction, place apex of the prism upward, 
in front of the right ej'e, and increase its strength till the 



INSUFFICIENCIES OF THE OCULAR MUSCLES 259 

patient sees double. For example, say the patient overcomes 
S° prism, but not 4°. His right sursumduction is 3°. The left 
sursumduction is obtained by placing apex of the prism 
upward, in front of the left eye, just as in the right. 

To measure deorsumduction, place apex downward, in front 
of the right eye, and increase its strength till the patient sees 
double, to get right deorsumduction ; and, to get left deorsum- 
duction, place apex down, in front of the left eye, and increase 
its strength till patient sees double. 

It is customary in practice to measure only the adduction, 
abduction, and sursumduction. 

The old equilibrium test^ of Von Graefe, that is, where a 
vertical diplopia is first produced in order to measure the 
strength of the muscles that move the eye in the horizontal 
plane, and a horizontal diplopia is produced in order to meas- 
ure the muscles in the vertical plane, is very defective, and 
gives exaggerated results in nearly every case. This is due to 
the fact that the instant you produce a diplopia with prisms 
you at the same instant take away from the eyes the desire, 
and, to a certain extent, the power, of fusing the images in the 
two eyes. As the desire and the capacity of fusing the two 
images into one, that is, of obtaining single binocular vision, is 
the greatest stimulus the eyes have for keeping themselves bal- 
anced and in equilibrium, this equilibrium test, at the very 
outset, places the eyes in the most unfavorable condition « for 
testing for equilibrium or balance. This test is to be con- 
demned therefore. The simple prism tests for ascertaining the 
power of adduction, abduction, sursumduction, are much more 
reliable. 

If I am not satisfied with the simple prism tests, I find the 
amplitude of convergence after Landolt's method. To get the 

1 This same test was later much used in America by Stevens and his pupils. 
Within the last few years, however, Stevens has invented an instrument for 
measuring the muscles, whereby he avoids diplopia in the beginning of the test. 



260 THE REFRACTIOX OF THE EYE 

maximum convergence, his method is to bring a narrow line of 
light (obtained by putting a metallic shield round a candle, 
and cutting a vertical slit in this shield three millimeters wide), 
toward the eyes, in the median plane, until the patient sees it 
double. Then he measures the distance from the eyes on a 
tape marked in centimeters. This number of centimeters di- 
vided into a hundred gives the number of meter angles of con- 
vergence of the eyes for the near point. For example, say the 
line of light ^ was brought to the distance of five centimeters 
when it doubled. Five divided into one hundred gives twenty, 
the number of meter angles of convergence for this distance 
(^punetum proximum). 

But, to get the minimum amount of convergence of which 
the eyes are capable, we must resort to measurement by prism 
divergence ; for it is a well-known fact that most eyes can 
diverge slightly even after their visual lines are parallel. As 
the distant point of convergence (^punetum remotum^ is at 
infinity when the visual lines are parallel, it is manifest that, if 
the eyes can diverge further after this, the distant point, under 
such circumstances, must be beyond infinity ; or, if prolonged 
backward, the visual lines would converge to a point back of 
the eyes, evidently not to be measured by tape or rule. In 
order to get this point, therefore, we measure the amount or 
angle of deviation that the eyes are capable of. as in measuring 
for abduction, by means of prisms with apex outward — the 
strongest prism the patient can overcome before seeing double, 
divided by two, representing the angle of deviation.^ Then, 
from the size of the angle of divergence, according to a simple 
formula given by Landolt, we can calculate the distance of the 
distant point (^punctum remotimi) back of the eye. 

1 A black line on a white piece of paper serves the same purpose. 

2 The reason that the prism has to be divided by two is because a prism 
causes a deviation of only one-half the number of degrees in the prism. At 
least, this holds true in prisms of low or moderate degree of power. 



mmm 



INSUFFICIENCIES OF THE OCULAR MUSCLES 261 

As Lanclolt says: -'It is not difficult to show the relation 
existing between the strength of any prism and the number of 
meter angles which expresses the deviation produced. For a 
base line (or distance between the centers of rotation of the 
two eyes) of 58 millimeters, as in children, a meter angle cor- 
responds to r 39' 39'' — say 100'. 

" The deviation produced by a prism may be taken as half 
its angle of opening, which is marked on each prism in our trial 
cases, or on the hand of the double prism. Therefore, a prism 

of X° will produce a deviation of — - or of ■ — It is only 

necessary to divide this value by 100 in order to obtain, the 

corresponding number of meter angles: — — — • 

jli X lUU 

" This formula reduced to its simplest expression becomes 

-— —, that is to say, we have only to multiply the number of the 

prism hy 3, and divide the prism hy 10, in order to find in meter 
angles the deviation for a base line of E>S millimeters.^ 

" When the prism is held before one eye only, as in the 
determination of the minimum of convergence by the double 
prism, its action is divided between the two eyes. The total 

deviation — — gives for each eye — -. A prism of 6° produces 

a deviation of yf = 1.8 meter angles. But if both eyes con- 
cur to neutralize this effect, each eye need only change its 
direction ^^= 0.9 meter angle. It is only when the prism of 
6° is placed before each eye that the full result of 1.8 meter 
angles is obtained ; always, of course, for a base line of dS 
millimeters. 

"When the base line is longer, for example, 64 mm., as in 
adults, tlie meter angle becomes 1° 50' = 110', and the formula 

3 X 

becomes — — for the deviation corresponding to the prism of X°, 

1 Italics mine. 



262 THE KEFRACTION OF THE EYE 

or '-—- for the effect produced on each eye when the prism i& 

placed before one qjq only."^ 

Say in the above case, when the positive convergence was 
20 meter angles, the patient was able to overcome only 4° 
prism, apex outward. We will assume also that it is the case 
of a child with a distance between the centers of rotation 
of the two eyes of 58 mm. Landolt's formula would give 

— —^=1.2 meter angles of divergence (negative conver- 
gence). As we placed the 4° prism in front of but one eye, it 
equalled the strength of only 2° prism in front of both eyes,. 

4x3 
when our formula would be — 0.6 meter angle. 

Xow to get the amplitude of convergence we subtract the 
0.6 meter angle of divergence (negative convergence) from 
the 20 meter angles of positive convergence which we got 
by actual measurement • with the tape. This would give 
20.6 meter angles as the amplitude of convergence in the 
above case. 

Landolt has given 10.50 meter angles as the average ampli- 
tude of convergence, and I may say I have found his the most 
satisfactory way of measuring the convergence. Even when 
the measurement b}^ means of prisms (prism convergence test) 
indicates an insufficiency, if the amplitude of convergence 
comes near the normal, I have found that simply correcting 
the error of refraction is all that is necessary in most cases,, 
aided in some, however, by exercise and tonics. 

Strength of the different ocular muscles as expressed in adduc- 
tion^ abduction^ sursumduetion ; their direct and relative values. — 
Incidentally, I may remark here that our notions in regard to 
the strength of the different ocular muscles, as expressed in 
the terms adduction, abduction, sursumduetion, and their rela- 

1 Landolt, Refraction and Accommodation of the Eye, p. 287. 



INSUFFICIENCIES OF THE OCULAR MUSCLES 263 

tive values, have undergone some change since the publication 
of a paper by Bannister on the "Dynamics of the Ocular 
Muscles," in the Annals of Ophthalmology/, January, 1898. 
Bannister measured the muscles in the eyes of one hundred 
soldiers in the United States army who were in rugged health; 
in fact, had to undergo the most rigorous physical examination 
before enlistment. They were required to read |-^ (Snellen) 
with each eye and without glasses before entering the service. 
So he had ideal subjects for testing the ocular muscles. 

The results he arrived at vary widely from those laid down 
by most authorities, both as to the actual strength of the 
different muscles and of their relative values. As his experi- 
ments were made on absolutely healthy subjects, so far as 
physical examination was able to decide, on eyes with perfect 
vision and no asthenopia, and the tests made with much care, 
they must be given great weight. Bannister cites Risley's 
paper of similar measurements made on a series of twenty-five 
non-asthenopic persons, and says he is the only one other than 
himself to make such examinations in the healthy non-asthe- 
nopic subject. I may say, however, that Roosa,i in 1890,. 
reported a series of 103 such cases, the examinations having 
been made for him by Dr. A. B. Deynard with the phorometer 
of Dr. Stevens, and after his method of testing. " Out of the 
103 cases, 17, or sixteen per cent, were found to have muscular 
equilibrium ; 84, or eighty-one per cent, had a want of mus- 
cular equilibrium, so-called heterophoria ; of these 27, or 
twenty-six per cent, had deviation outward, exophoria, insuffi- 
ciency of the interni ; and 74, or seventy-one per cent, ex- 
ophoria in accommodation ; 16, or fifteen per cent, had deviation 
inward, or esophoria, insufficiency of the externi ; 7 had es- 
ophoria in accommodation ; 11, or ten per cent, had hyper- 
phoria, a tendency of the right or left visual line upward : 24 
had hyperphoria in accommodation. A reexamination of rive 

1 Med. liecord, April 19, 1890. 



264 THE REFRACTIOX OF THE EYE 

of these patients all shoAvecl a cliange in the muscular examina- 
tion from that found at first. This is an important observa- 
tion, since it proves, as asserted by Starr and others, that the 
muscular power in the same eyes is not fixed, but variable.*' 

Adduction^ as measured by prisms (prism convergence), the 
common method pursued in office practice, bases out before 
the eyes, amounts for the distance vision to from 35° to 50°. 
At least this is the standard given by most authorities. Ban- 
nister, in his experiments on one hundred healthy, non-asthe- 
nopic subjects, gives the average adduction as only 14.1°. He 
says in regard to it : ''I am perfectly willing to place myself 
upon record as asserting that the teaching of the authorities 
that healthy eyes should show upon demand a prism conver- 
gence for distance of 30°, or 35° to 50°, is absolutely misleading 
and erroneous. In my series of examinations the highest 
amount of adduction for 6 meters reached was 26°, and this 
amount could only be obtained in one case, and that, too, only 
after most careful effort. We are told that in our office con- 
sultations our patients should show this amount of adduction 
(30° or 35° to 45° or 50°), and that if they do not exhibit it we 
must consider their convergence to he weak. If we accept as true 
the standard given above, every one of my healthy cases should 
he charged ivith convergence insufficiency.'^ 

He, however, remarks that b}^ prism practice most, if not 
all, of these could be made to show an adduction of 50°. 
•'But," as he again says, "that is not the point at issue." It is 
the first test, and not when they have had previous tests, prism 
practice, if you please, of which he speaks. 

Ahduction^ as measured b}^ prisms (prism divergence), for 
distance amounts, as a rule, to 8°, according to the older 
standards. Risley gives the same amount for healthy non- 
asthenopic subjects. Bannister gives 7° as the average abduc- 
tion for his one hundred healthy soldiers, but in manj' of his 
cases it was considerably less. In this connection he calls 



INSUFFICIENCIES OF THE OCULAR MUSCLES 265 

attention to the claims made by Noyes, Duane, and others that 
abduction should not fall below 6° for the distance, and that an 
abduction of less than 5° will in most cases be pathological. 
In other words, that an insufficiency of the external recti is 
present. 

Bannister says, " If these views are correct, twenty-two, or 
at least seventeen, of my absolutely healthy cases, would fall 
in the pa.thological class." • He does not believe them to be 
in this class, however, for every one of the twenty-two cases 
showed perfect muscle balance for the near point, and only 
nine a want of balance of the muscles for the distance, and 
that in only a slight degree. 

The same author also explodes the old idea that for the 
near point we may expect an insufficiency of the internal recti 
of about 5° prism, and that such a condition is physiological 
(Duane). In fact, he demonstrates that muscle balance is more 
frequent for the near point than for the distance, for in his one 
hundred cases he found perfect muscle balance for the distance 
in but sixty cases, while for the near point it was present in 
eighty-two cases. Moreover, he showed in the thirteen cases 
that had a divergence excess for the distance that eleven of 
them had perfect muscle balance, and only two of them showed 
slight diverging tendency for the near point. This is just the 
reverse of what would be expected according to the old stand- 
ards, and can be explained only on the ground. Bannister 
thinks, "that orthophoria is the physiological state for the 
near ; " and this, " notwithstanding the opposite opinion held 
by such eminent authorities." 

In regard to the ratio between adduction and abduction, or 
their relative strength as measured by prisms. Bannister thinks 
that there cannot be any definite relation fixed; and is of the 
opinion that older standards of 6 to 1, or 7 to 1, without pre- 
vious training of the convergence with prisms, is much too 
high. His own results would indicate that relation in healthy. 



266 THE REFRACTION OF THE EYE 

non-astlienopic subjects to be about 2 to 1, since the average 
adduction in his cases was 14.1°, while the average abduction 
was 7°. 

Sursumduction, as measured by prisms, base down, amounts 
to 2° to 4°. . 

Deorsumduction, as measured by prisms, base up, amounts to 
2° to 4°. 

Bannister, in his healthy subjects, gave 2° as the average, 
both of sursumduction and deorsumduction, and says in regard 
to their relative strength, " It seems well settled, also, that 
the power in each direction of the vertical plane is about the 
same^ and that deGrsitmduction shoidd not be expected to exceed 
the antagonistic function as held by some.'' 

Since I have quoted so liberally from Bannister's paper,^ I 
give his conclusions, which, since they are based on the ex- 
aminations made in perfectly healthy subjects with non-asthe- 
nopic eyes, must be admitted to form a good standard for 
abnormal conditions : — 

"1. The degree of adduction (prism convergence) given by 
most writers as proper for 6 meters, cannot be reached by hecdthy 
eyes except after practice in the use of j^^risms. Hence the stand- 
ard is too high for attainment in the first office examination, 
and hence the method of measuring the convergence by adductive 
p>risms is unreliable and misleading. 

"2. That t\\Q prism convergence for near (33 centimeters) is 
also misleading, and is not an accurate test of the real power of 
convergence, 

"3. That the determination of the punctum jyroximum of con- 
vergence^ and the calculation of the maximum convergence after 
the method of Landolt, are the only true tests of the real poiver 
of convergence., or the p)ositive convergence. 

" 4. That, contrar}^ to the generally received views, abduction 
(prism divergence) for distance can fall well below 6° in 

1 Annals of Ophthalmology, St. Louis, January, 1898. 



INSUFFICIENCIES OF THE OCULAR MUSCLES 267 

]iealtliy eyes, and that, consequently, it is wrong to assume upon 
this basis alone that such cases are pathological. 

" 5. That there exists in healthy eyes no positive, definite 
relation between prism convergence and prism divergence for 
distance, and that it is not correct to claim that such eyes 
should without practice ivith prisms show at 6 meters a ratio 
between these functions of 3 to 1, or 7 to 1, in favor of con- 
vergence, not permitting abduction to fall below 6°. 

" 6. That we may expect sursumduction and deorsumduc- 
tion for distance to be about the same in degree ; in about 70 
per cent of healthy eyes each function reaches 2° (prism) 
in amount. 

" 7. That in healthy eyes orthophoria exists in about 60 per 
cent of the cases /or distance^ and in about 82 per cent for near, 
and that it is wrong to hold that orthophoria for near is abno7nnal, 
and to he vieived with suspicion. 

" 8. That in about 40 per cent of healthy individuals who 
have never had a symptom of eye trouble there may be found a 
slight heterophoria for distance., and that, therefore, we should 
not assume that every patient showing a slight degree of im- 
balance is on that account alone in a serious condition." 

The mere fact, however, that the examinations from which 
these conclusions of Bannister are drawn were made on eyes 
with little or no refractive error, without asthenopic symptoms, 
and in healthy subjects, must be borne in mind ; for it may 
be stated as a general principle that hypermetropic errors of 
refraction favor convergence, while myopic favor divergence, of 
the eyes. Hence, we may find a predominance of the one or the 
other, accordingly as the eye is hypermetropic or myopic ; and 
this should be remembered when refractive errors are present. 

But, taking refractive cases as they come, I must say my 
experience as to the strength of the muscles, actual and rela- 
tive, more nearly agrees with that of Bannister's than with the 
ordinary standards as given in the text-books of to-day. 



268 THE REFRACTIOX OF THE EYE 

As a rule, strabismus cases should not have glasses fitted 
until three years of age, for under this age they can seldom be 
made to wear the glasses ; or, if they do wear them, be made 
to look through them ; they, most of the time, looking under or 
over them. Then again, the danger of a young child break- 
ing the glasses and injuring the eyes is not to be forgotten. 
I have fitted two cases of glasses at three years of age ; 
but, in each case, the child was very tractable, and wore the 
glasses as directed by the mother. Dr. Dennett, of this 
city, has, I believe, fitted children at the tender age of two 
years. ^ 

Of course, as soon as the eyes are adjusted to glasses they 
are in a better condition to be used together, and the stimulus 
to single binocular vision is much enhanced, if amblyopia is 
not too marked. 

Incidentally, in this connection, I might say that, with rare 
exceptions, no operation should be done on a squinting eye in 
a child under four years of age ; and, as a rule, it is safer to 
wait till the patient is five or six years old. It is a well- 
established fact that many children " grow out " of a conver- 
gent squint. I have seen several patients who gave a history 
of squinting in childhood, but who had perfectly straight eyes 
when they came under my care in later life, and without 

1 In reply to a note from me, I received the following letter from the 
doctor : — 

" Dear Doctor Davis, — 

"In 1889 I had a little girl for a patient who was fourteen months old, and 
who had had a well-marked convergent strabismus for some weeks. She had 
by ophthalmoscopic examination, — upright image, — Hm. + 2. 0. U. 

•' I ordered glasses, and asked the mother to see if she could make the child 
wear them. I have not seen the child since, but the mother told me that the 
glasses were worn most of the time for two weeks, when the squint disappeared, 
and the baby was allowed to go without them. 

" The mother was an intelligent woman, and I believed her. 

" Yours, etc." 



METHODS OF MEASURING STRABISMUS 269 

having had any operation on the eyes.^ While writing this 
chapter, two such cases have come under my care, both of 
whom had squinted in childhood, but both had recovered from 
it without glasses and without operation. In each case there 
was a high degree of compound hypermetropic astigmatism, 
with marked amblyopia in the eye that had squinted. Both 
cases are reported in this chapter farther on. 

Dr. Roosa tells me he has the history of at least one hun- 
dred cases who had squinted in childhood, but subsequently 
recovering without operative procedure. In fact, testimony of 
like character is to be had on all sides ; so it behooves us, in 
strabismus cases, not to be in too great a hurry about operat- 
ing, especially in convergent strabismus. It is best first to 
begin by fitting the patient correctly to glasses under a mydri- 
atic, and letting these glasses be worn continuously for a num- 
ber of months, or years, if the patient is very young, before 
operating. 

For measuring the amount of strabismus, there are two or 
three very simple methods : (1) By means of a very simple in- 
strument, the strabometer of Laurence, represented in the cut 
below, the deviation of the eye can easily be measured. This 
instrument is numbered in millimeters from the center, 0, lat- 
erally in each direction. By placing this instrument directly 
beneath the deviating eye, while the good eye is fixed on some 

1 1 have seen one case, in fact, within the year, where a convergent strabis- 
mus developed, into a divergent strabismus, and without any operative procedure 
whatever. The patient, a gentleman of much intelligence, aged thirty-live years, 
gave a history of marked inward squinting of his left eye when a child which got 
well of itself, without glasses and without operation, by the time he was twelve 
years of age. Although he always saw poorly with the left ej- e, he did not have 
glasses fitted till twenty-one years of age, which glasses he has worn since. 
About three years ago he noticed that his left eye turned outward at times, 
and for the last few months continually. There is a divergence now of 10^. 
R. V. = f§ : 1-0- W. + 1 D. + .75 cyl., 90° ; L. V. = ^^^ : j^ir W. -H 3 D. + 1 D. 
cyl., 90°. Binocular single vision is absent. There is no lesion in the fundus of 
either eye. This is the only case of the kind that has come under my observa- 
tion. 



TO 



THE KEFRACTIOX OF THE EYE 




distant point, and noting the number of millimeters distance 
the center of the cornea is from the center of the instrument, 
we at once ascertain the amount of the deviation in millimeters. 
As each millimeter of deviation represents 
rouglily an angle of 5^ we can reduce the 
linear deviation to an equivalent expressed 
in degrees, by simply multiplying the num- 
ber of millimeters of deviation by live : for 
example, say the linear deviation was three 
millimeters, this reduced to degrees would 
be 15^ and so on.^ 

(2) The extent of deviation or squint- 
ing of an eye may be measured with the 
perimeter. Place the patient in front of 
the instrument, with the deviating eye in 
Fig. lOL— Strabometer Hue with the Center of the arc, just as if 
to take the lield of vision. Leave both 
eyes open, and have the good one directed to a distant object 
(20 feet) directly in front ; then carry a candle along the arc 
of the instrument until the image of the flame is at the center 
of the cornea of the deviating eye. The position of the candle 
on the arc marks the number of degrees of deviation. 

(3) A simple method, without the use of any instrument 
whatever, is as follows : Have the patient look at a distant 
object directly in front of him, then make an ink-dot on the 
lower lid of the deviating eye. directly below the outer margin 
of the cornea: also a dot on the lid just below tlie outer mar- 
gin of the cornea of the straight eye. Xow cover the straight 
eye with a card, and let the patient fix the object with the bad 
or crooked eye. Of course, the eye will liave to move from its 
original position to do this, and the good eye back of the card 
will squint as the bad eye had when uncovered. Again mark 

1 Perhaps each milUmeter of deviation vrould be more nearly represented 
bv an ansle of 5^-, rather than the even number 5'. 



ILLUSTRATIVE CASES 271 

the position of the outer margin of the cornea on the lower lid 
of the bad eye ; also the position (back of the card) of the outer 
margin of the cornea of the good eye on the lower lid. The 
deviation in each eye will be found to be exactly the same. 
That in the bad eye is called the primary deviation, that in the 
good eye the secondary deviation. The distance between the 
two dots on the lids will be the amount of deviation. To get 
it in degrees, multiply the number of millimeters by 5 ; for 
example, say the distance between the dots on each side is 
4 millimeters. This multiplied by 5 gives 20, the number of 
degrees of deviation. 

If, as sometimes happens, the power of fixation is lost in 
the squinting eye, even when the good eye is covered, this last 
test cannot be made. The approximate amount of the devia- 
tion can be determined in such cases by having the patient 
look at a distant object directly in front of him, then measure 
the distance between the external canthus aiid the outer edge 
of the cornea in each eye. The difference between the two 
amounts is the extent of the deviation of the squinting eye 
(Fuchs). 

For more complete tests for determining the amount of 
deviation or squint in an eye, and for the .indications for oper- 
ating on such eyes, I must refer the reader to the larger text- 
books. An intimate knowledge of the anatomy and ph3^siology 
of the muscles of the eye, as well as an acquaintance with the 
refractive conditions, is necessary for a full understanding of 
the subject. 

Case XCV. Convergent strabismus left eye; Simple Iiyper- 
metropia both eyes; Cure by means of glasses and a mydriatic. — 
July 7, 1892, Hugh G., aged four years, in good health, was 
brought to me by his mother on account of the left eye turning 
toward the nose. The eye has squinted since he was a baby. 
He had diphtheria when one year of age, but the eye turned 
before lie had diphtheria. The patient has a twin sister and 



272 THE REFRACTIOX OF THE EYE 

a younger brother, whose eyes are perfectly straight. Father 
and mother's ejes are straight. 

Ophthalmometer. — Astigmatism with the rule, .50 D., axis 
90° + 180° — each eye. As the patient was too young to test 
with the test cards, I made no attempt at subjective examina- 
tion. 

Ophthalmoscope. — H. 2 D. right eye; H. 4 D. left eye. 
Ordered atropine solution, 2 gr. to ^i, to be used three times a 
day for one week. Before instilling the atropine solution, I 
measured the amount of deviation, and found it to be between 
15° and 18°. Under atropine, the ophthalmoscope showed H. 
4 D. right, and H. 5 D. left. The retinoscope confirmed this. 
A -f 3.50 D. spherical glass right, and + 4.50 D. left, were 
ordered for constant wear ; and one drop of the atropine solu- 
tion, in each eye, once a day, was continued for two weeks. 
At the end of that time the eyes were much improved ; atro- 
pine, one drop every other day, was used for two weeks longer, 
then it was discontinued altogether. At the end of six months 
the patient had perfectly straight eyes with the glasses on. If 
the glasses were removed, the patient would turn the left eye 
inward, but not as far as when first seen. 

I have seen this child from time to time for the last seven 
years, and the eyes remain perfectly straight with glasses, but 
have a tendency to turn for the near point unless the glasses 
are on. 

When the patient arrived at the school age and knew his 
letters, I tested both eyes carefully for acuteness of vision, to 
see if any amblyopia was present in the eye that had squinted. 
The vision in each eye was |-§- (Snellen) with his glasses on. 
If he ever had amblyopia in the left eye, it had disappeared 
with use and the aid of the glasses. Single binocular vision 
is present. 

Operative proceedings in this case when first seen would 
have been unwise. The motility of the eye, the acuteness of 



ILLUSTRATIVE CASES 273 

vision in each eye (when it can be taken), the kind of squint, 
alternating or fixed, are all factors which should be weighed 
before any operation should ever be undertaken. 

The ophthalmometer was a valuable means for eliminating 
the factor of corneal astigmatism at the outset of the case. 
Retinoscopy was of value, also, as atropine -had to be used. 
In fact, it is in just such cases that these objective tests are of 
such great importance. 

Case XCVI. Periodic convergent strabismus right eye ; 
Simple hypermetropia each eye ; Cure effected in three months hy 
means of glasses alone. — November 27, 1898, Wm. M., aged 
seven years, in §ood health, came to the clinic of Drs. Lewis 
and Van Fleet, because of squinting of the right eye in- 
ward at times for the last year. None of his family is cross- 
eyed. As is often the case, the mother attributes the cause to 
a fall on the head when the patient was a baby, although the 
eye did not begin to squint till he was about six years of age. 
The right eye deviates inward about 15°. 

Oj)hthalmometer. — Astigmatism with the rule, 1 D., axis 
90° + or 180° - in each eye. 

Test cards and trial lenses. — 

R. V. = 1^ : f-l W. + .50 D. cyl., 90°. 
L. V. = 1^ : ff W. + .50 D. cyl., 90°. 

Reads Jaeger No. 1 from 4 to 12 inches. 

Ophthalmoscope. — H. 2 D. in each eye. 

Ordered atropine solution, 2 gr. to 5i, to be instilled, three 
times a day, for four days, and to return for a second test. 

Second test : ophthalmometer shows astigmatism with the 
rule, .50 D., axis 90° + or 180° - in each eye. 

Test cards and trial lenses. — 

R.V. = fJ:||-W. +3D. 
L.V. =fMlW. -I- 3D. 



274 THE REFHACTION OF THE EYE 

Ophthalmoscope. — H. 3 D. in each eye, 

A plus 3 D. sphere was ordered for each eye, to be worn 
steadily. In three months' time this patient ceased to squint 
altogether, although he went to school, and used the eyes for 
close work. 

It is hardly. necessary, I suppose, to say that a periodic 
squint, in young subjects es^Decially, should not be operated 
upon. Certainly not until glasses have been given a thorough 
trial ; aided, if need be, by having a weak solution of atropine 
instilled into the eyes, once a day, for a few weeks at a time ; 
then intermit, and repeat once or twice. Covering up the 
good eye for half an hour, once or twice a day, is valuable in 
these cases. The stereoscope is valuable also. If, after a few 
weeks, or months at furthest, the squint is not improved, but 
grows worse, becoming a permanent squint, an operation is to 
be considered, and no more time should be wasted. 

In the case just reported, the ophthalmometer showed astig- 
matism of 1 D., before the mydriatic was used, and the patient 
accepted .50 D., the correct amount after deducting .50 D., as 
is ordinarily done in astigmatism with the rule. After using 
the mydriatic, however, the instrument showed only .50 D., 
and the patient accepted only a spherical glass, as is customary 
when there is only .50 D. of corneal astigmatism with the rule. 
This discrepancy is to be explained in one of two ways : first, 
in the first test there might have been an error in observation, 
which seems unlikely, as the patient accepted + .50 D. cyl., 
90° ; second, when the mydriatic was used it relaxed the accom- 
modation, the convergence was relaxed at the same time, and 
this relaxation of the convergence took some pressure off the 
horizontal meridian of the cornea, and, in that way, lessened 
the astigmatism, perhaps'. I rather incline to the latter opin- 
ion. That the straight muscles do exert some influence on the 
curvature of the cornea is proved by a case reported by me in 
the 3Ia?ihatta7i Eye and Ear Hosp)ital Reports^ 1895, p. 49. 



ILLUSTRATIVE CASES 275 

A favoring factor in this case, in aiding the eyes to become 
straight without operation, was the fact that there was no 
amblyopia present in either eye, for this reason the fusion of 
the images of the two eyes was- greatly facilitated, and the 
desire for single binocular vision increased. Single binocular 
vision was restored in this case. 

.Even where the squint is constant, but where the patient 
squints first one eye, then the other, at will, and without the 
necessity of covering either eye, — the so-called alternating 
squint, — the visual acuity is apt to be the same, or nearly the 
same, in each eye, and to be very good, -|-§- or better. In such 
cases, the chances for cure with glasses alone are much better 
than where amblyopia is present in one eye. 

Case XC VII. Convergent strabismus right eye ; Compound 
Ifiypermetropic astigmatism both; Amblyopia hoth^ hut more 
marked m the right; Glasses and one operation necessary for 
a cure. — September 11, 1891, Grace C, aged eight years, came 
to the clinic of Drs. Lewis and Van Fleet because of squint- 
ing of the right eye, which has squinted constantly for four 
years. She has not had treatment of any kind thus far. 

Ophthalmometer. — Astigmatism with the rule, 1 D., axis 
90° + or 180° - each eye. 

Test cards and trial lenses. — (Under atropine mydriasis). 

R. V. = f^\ : t;Vo W. + 1 D. + .50 D. cyl., 90°. 
L. V. = f^ : 1^ W. + 3 D. + .50 D. cyl., 90°. 

Ophthalmoscopic. — ■!!. 5 D. right eye ; H. 1 D. left eye. 

Ordered the glasses that were accepted under atropine, 
which were worn continuously for six months, but the squint 
remained. At the end of this time a tenotomy of the right 
internal rectus was done. The qjq was made perfectly 
straight with the operation, and by continued use of the 
glasses was kept straight, although single binocular vision 
was not restored. 



276 THE REFRACTIOX OF THE EYE 

It will be noticed that tlie amblyopia was marked in the 
right or squinting eye, while it was present to a moderate 
degree in the non-squinting eye. The ophthalmometer in 
such cases as this is very useful, for with so marked amblyopia, 
as was present in the right eye, glasses do not improve the 
vision much, no matter what glasses are given, yet it is 
important to give the correct glass. If we can meas- 
ure the astigmatism in such cases, and have that impor- 
tant factor satisfactorily disposed of, it greath' facilitates 
matters. 

Case XCYIII. Convergent strahismus riglit eye; Large 
amount of compound hypermetropic astigmatism in each eye^ 
more marJ^ed in the right eye; Amblyopia in each; Cured by 
glasses and one operation. — October 9, 1894, J. R., aged nine 
years, came to the clinic of Drs. Lewis and Van Fleet to have 
the right eye straightened. The right e3^e has turned inward 
since he was a small child, and now has a squint of 20° or 
more. He can fix with the squinting eye when the good one 
is covered. None of the family but himself ever had '' cross- 
eye."' 

Ophthalmometer. — Astigmatism with the rule, 2 D., axis 
120° + or 30° - right ej^e ; 1.50 D., axis 60° -j- or 150° - left 
eye. 

Test cards and trial lenses. — 

^' ^^' = M '- U + "^^^- + -3 D. + 1.50 D. cyl., 120°. 
L. V. = ^Vo • H + ^^'- + ^ D- + 1 D. cyl., 60°. 

Ophthalmoscop)e. — 'R. 3 D. at 120° and H. 5 D. at 30° 
right e3-e ; H. 4 D. at 60° and H. 5 D. at 150° left eye. 

Ordered atropine solution, 4 gr. to 3i, three times a day for 
four days. 

Test under atropine : ophthalmometer showed the same 
reading as in the first test. 



ILLUSTRATIVE CASES 277 

Test cards and trial lenses. — 

R- ^- = 2-Vo : f PV. + 4 D. + 2 D. cyl., 120°. 
L. V. = 2^ : f ^ W. + 5 D. + 1.50 D. cyl., 60°. 

OpJithalmoscojJe.—B.. 4 D. at 120° and 6 D. at 30° right 
•eye ; H. 5 D. at 60° and H. 6 D. at 150° left eye. 

Two days later a third test was given, the atropine having 

been stopped. The ophthalmometer showed the same reading 

as on previous occasions. With the test cards and trial lenses 

the patient accepted the same spherical glass as when under 

atropine, but one-half diopter less of astigmatic correction. 

Ordered : — 

+ 4 D. + 1.50 D. cyl., 120° right; 

+ 5 D. + 1 D. cyl., 60° left. 

Two days later a tenotomy of the right internal rectus 
muscle was done. With the glasses on, the eyes were per- 
fectly straight. One month later there was a slight conver- 
gent squint in the right eye, but not enough to notice, except 
on close inspection. 

No further operative procedure was deemed necessary. 
Glasses were ordered to be worn continuously. The patient 
did not have single binocular vision. 

Case XCIX. Marked convergent strabismus in each eye., 
more 'pronounced in the right (50° right and 25° left) ; Poiver of 
fixatiofi lost in the right, and m the left motion outward is limited 
also., the patient carrying her head to the left in order to see 
straight ahead: small amount of hyper metropia ; Cured by tenot- 
omy of the internal recti muscles, and advancement of the right 
external rectus. — Violet J., aged four and one-half years, Avas 
brought to my clinic at the Post-Graduate School, in October, 
1897, by her mother, to liave the child's eyes straightened, 
because the children at the kindergarten made fun of her. 
The patient's eyes have both turned inward since she was a 
baby. At present the right eye turns far in (50°) and cannot 



278 



THE REFRACTION OF THE EYE 



be turned out to the median line. The left eye turns inward 
25°, and motion outward is limited, so much that the patient 
carries her head to the left in order to see objects straight 
ahead. Fuchs, quoting Arlt, explains the oblique position of 
the head in such cases as follows : " As convergence is an 
associated movement of both interni, this impulse affects both 
at once, so that, owing to their excessive contraction, the visual 
lines would cross in front of the object ; but as the patient 
then w^ould fail to have direct vision of the object with either 
eye, he turns his head a little to one side. He thus gets the 
object into the line of vision, g^ of one, and that the better eye 

(Z Fig. 102), Avhile the 
line of vision, g\ of the 
other eye shoots off so 
much the farther from 
the object. Thus the 
patient secures fixation 
5 with one eye at all 
events, although both 
interni are still strongly 
contracted. It is owning 
to the last-named fact 
that the increase in the 
power of adduction de- 
velops in the course of 
time in both eyes. By 
this fact, too, is explained the oblique position of the head in 
those affected with convergent strabismus — such j)ersons car- 
rying the head turned toward the side of the healthy eye."^ 
The right eye in the present case could not be made to fix 
when the left was covered, the marked contraction of the 
internal recti preventing ; and, even with the left, the head 
had to be turned in order to fix the object. 

1 Fuchs, Text-Book of Ophthalmology, p. 573. 




Fig. 102. — (After Fuchs.) ShoTving oblique po- 
sition of the eyes and head in convergent 
strabismus of both eyes. 



ILLUSTRATIVE CASES 279 

The external movements of both eyes were not only limited 
relatively as compared to the internal movements, but actually, 
as already remarked above. 

OpMhalmometer . — Astigmatism with the rule, .50 D., 90° 
+ or 180° — left eye. The right eye could not be measured 
with either the ophthalmometer or retinoscope, because the 
patient could not turn the eye out far enough ; and to measure 
the left eye, the patient had to turn her head to the left in 
order to give a front view of it. 

Ophthalmoscoi^e. — H. 2D. in each eye. 

As the child did not know her letters, no subjective test 
was tried. Atropine was ordered, and after three days a 
second test was made. The ophthalmometer gave the same 
reading as before. The ophthalmoscope showed H. 2.50 D. 
each. Ordered + 2 D. sphere for each eye. I then did a te- 
notomy on each internal rectus. The eyes were not straightened 
with this, but I refrained from making an advancement of the 
right external rectus at this time to see how much effect the 
tenotomies would have. Atropine was used once a day for 
the next month, and the glasses were worn continuously. After 
six weeks the left eye was straight, but the right still turned 
in considerably, 20°, so a second tenotomy of the right internal 
rectus, with advancement of the right external rectus, was 
done by my assistant. Dr. J. R. Nelson. The squint was over- 
corrected slightly, on purpose, and for the first few weeks after 
the operation it was noticeable, especially with the glasses on. 
The glasses were ordered discontinued. Six months after the 
advancement the eyes were perfectly straight, and the child 
was ordered to leave off the glasses. ^ 

This patient was younger than I like to operate on for 

1 The reason for taking the glasses off in this case is obvious. The squint 
having been slightly over-corrected by the advancement, by taking oft' the 
glasses the patient had to use her accommodation, and this stimulated con- 
vergence with the result that the eyes were held perfectly straight. 



280 THE REFRACTION OF THE EYE 

squint, but as the strabismus was so pronounced and in each 
eye, and because she was an object of ridicule by her school 
companions, I deemed it best to operate. At this writing, 
eighteen months after the advancement, the eyes are still 
parallel, and the patient carries her head straight. She does 
not have single binocular vision, however, as the right eye is 
very amblyopic, as shown by tests with figures which the child 
now knows. 

Case C. Divergent strabismus right eye; Antimetropia ; 
Compound r}iyopie astigmatism right and compound hyperme- 
tropic astigmatism left eye ; With glasses the squint ivas relieved 
and single hinocidar vision obtained for distant vision^ hut not 
for near. — June 7, 1897, Mrs. A. M., aged thirty-one years, 
in good health, has always had trouble with her eyes, and when 
she reads or sews the eyes ache. The right eye has turned 
outward at times for the last fifteen years. 

Ophthalmometer. — Astigmatism with the rule, 2D., axis 
80° 4- or 170° - right eye ; .50 D., axis 100° + or 10° - left eye. 

Test cards and trial 



K- ^'=^'' I* W. - 1 D. - 1.50 D. cyl., 170°. 
L. V. = 1^ :|-^W. + .25D.+ .25 D. cyl., 100°. 

Reads Jaeger No. 1 from 6 to 15 inches with the left eye. 
The patient does not use the eyes together for reading, either 
with or without the glasses. For distant vision with the glasses 
on the patient has single binocular vision, as shown by the test 
with prisms, to wit: ad. 10°, ab. 7°, sur. R. & L. 2°. Without 
the glasses she does not have single binocular vision. 

Ophthalmoscopic, —^l. 3 D. at 75° and M. 1 D. at 165° right 
eye ; H. 1 D. left eye. 

Because of a mild conjunctivitis alum was applied to the 
lids and an astringent wash prescribed. One week later a 
second test was made. 



ILLUSTRATIVE CASES 281 

Second test : Ophthalmometer. — Astigmatism with the rule, 
2.50 D., axis 75° + or 165° - right eye ; .75 D., axis 120° + or 
30° - left eye. 

Test cards and trial lenses. — 

I^- ^' = 2^^ '' f* - ^^- - •'^^ D. - 2 D. cyl., 165°. 
L. V. = f^ : If - W. + .25 D. cyl., 120°. 

Reads Jaeger No. 1 from 6 to 15 inches right, and Jaeger 
No. 1 from 4 to 10 inches left eye, but does not use the eyes 
together. The angle alpha is small in the right eye, being 2° 
positive, while it is 4° positive in the left eye. 

A third test agreed with the second, and — .75 D. — 2 D. 
cyl., 165° right, and + .25 D. cyl., 120° left, were ordered for 
constant wear. These glasses gave immediate relief from the 
asthenopia from which the patient suffered. One year later I 
saw the patient again ; she was entirely comfortable, the eyes 
were straight, and she had single binocular vision for distance, 
but not for near ; ad. 15°, ab. 6°, sur. R. & L. 2°. 

For a very interesting case of convergent strabismus in the 
myopic eye of an antimetropic case, which was corrected by 
glasses alone, see Case LXX in Chapter VI. 

Case CI. Divergent strabismus right eye; Simple hyper- 
metropic astigmatism in both; Correction of refractive error; 
Tenotomy right external rectus; Relief. — January 4, 1894, 
Henrietta M., aged thirty-three years, in fairly good health, 
gives the following history : — 

Four years ago she had an abscess at the lower end of the 
spine ; a year later had part of the coccyx removed, and six 
months later some more of the coccyx removed. By these 
two operations the spinal trouble was cured. In the mean- 
time, however, her eyes began to pain her when she did close 
work of any kind, and she had glasses fitted, which relieved 
her for a time, but they do so no longer. She says if the 



282 THE REFRACTIOX OF THE EYE 

right eye diverged at that time that the doctor did not tell 
her of it. At the present time the right eye diverges between 
6° and 10°. She is wearing + 75 D. cyl., 90° each. 

Ophthalmomete7\ — Astigmatism with the rule, 1.25 D., 
axis 90° + or 180° - each eye. 

Test cards and trial 



I 



R. V. = 1^ - : 10 _ w. + .75 D. cyl., 90°. 
L. y. = f^ - : ff - W. + .75 D. cyl., 90°. 

Reads Jaeger No. 1 from 6 to 18 inches with the left eye, 
and the same with the right if the left is covered. Angle 
alpha equals 2° each eye, j)ositive. 

Ophthalmoscope. — H. 1 D. at 90° and H. 2 D. at 180° each 
eye. 

A second test resulted in the patient accepting the same 
glasses as at first ; and since they corresponded exactly Avith 
the glasses she was already wearing, + .75 D. cyl., 90° each, I 
did not change them ; neither did I put this patient under the 
influence of a mydriatic, as is my custom in squint cases, 
because the patient had a divergent squint with hypermetropia. 
The mydriatic would have increased the squint, as would also 
the plus spherical glass fitted under its influence. Since the 
divergent squint had apparently developed while she was 
wearing the cjdindrical correction, and as she was a seamstress 
and wanted relief from a diplopia which manifested itself fre- 
quently in the last few weeks before coming to me, I advised 
an operation, to which she consented. Accordingly, on Janu- 
ary 10, 1894, I did a complete tenotomy of the right external 
rectus muscle, making a small opening in the conjunctiva and 
Tenon's capsule, but not dissecting back along the muscle and 
up and down, as usual, as I did not want to have an over- 
effect. 

Immediately after the tenotomy, and for three or four days 
following, the right eye as measured by prisms converged 10°. 



ILLUSTRATIVE CASES 283 

At the end of two weeks, not only were the eyes perfectly 
straight and single binocular vision present, but the patient 
could use her eyes with perfect comfort. 

January 4, 1898, four years later, this patient came to me 
again complaining of headaches, pains in the eyes, and an 
occasional diplopia, especially for near points. On examina- 
tion, the right eye showed a divergence of perhaps as much as 
5°, but after covering and uncovering the eye several times 
the squint would disappear. I tested the eyes again and 
found an increase in the amount of the astigmatism. The 
ophthalmometer showed astigmatism with the rule, 2 D., 90° 
+ or 180° - right, and 1.50 D., 90° + or 180° - left eye. 
The patient accepted + 1.25 D. cyl., 90° right, and -f 1 D. cyl., 
90° left. It will thus be seen that the corneal astigmatism 
liad increased .75 D. in the right eye, and .25 D. in the left. 
The patient by the subjective test accepted .50 D. more in the 
right and .25 D. in the left, than four years previously, and 
the glasses were ordered. I gave her full doses of sulphate of 
strychnine also, and after about six weeks' time the patient was 
again comfortable, and able to see and read. This was over a 
year ago, and at the present time the glasses enable her to do 
her work with comfort. Single binocular vision is present. 

Case CII. Divergent strabismus right eye; Myoina of high 
degree right and moderate degree left; Grlasses ; Tenotomy right 
external rectus ivithout advancement of the internal rectus; Cure. 
— December 1, 1898, E. H., aged twenty, has been near- 
sighted since a small child, was brought to me by her mother 
to have her right eye straightened. She has pains in the eyes 
at times. She is now wearing — 5 D. spherical glass before 
each eye. Not only does the right eye diverge about 20°, but 
there is a slight horizontal nystagmus present. The patient is 
extremel}^ nervous. 

Ophthalmometer. — Astigmatism with the rule, .50 D., axis 
90° + or 180°- right eye ; .75 D., axis 90° -f or 180^^- left eye. 



284 THE REFRACTIOX OF THE EYE 

Test cards and trial lenses. — 

-^' ^ • — 200 • 30 ^^ • ' -^* 

Reads Jaeger Xo. 1 at 10 inclies with tlie left eye. 

Ophthalmometer. — Isl. 14 D. right eye, with a posterior 
staphyloma; M. 8 D. left eye. 

Second and third tests resulted in the patient accepting the 
same glasses as found at the first test. Ordered — 9 D. right, 
and — 7 D. left. I did a complete tenotomy of the right 
external rectus. AVith the aid of the glasses and the simple 
tenotomy, the patient has perfectl}' straight eyes, though not 
single binocular vision. Usually these divergent squints, espe- 
cially in m3'opic eyes, rec^uire advancement of the internal 
rectus in addition to tenotomy of the external rectus. Four 
months after operation, the patient still had straight eves. 

Case CTII. Convergent strabismus right eye marked^ and to 
a moderate degree in the left ; Kyijermetropia right, compound 
hypermetropic astigmatism left eye ; Glasses; Tenotomy of inter- 
nal rectus of each eye ; Cure. — December 1, 1898, M. H., aged 
nineteen years, in good health, a sister of the patient just 
reported above, with myopia and divergent squint in the right 
eye, was brought to me at the same time as her sister to have 
her eye straightened. Her mother tells me that her eyes 
have turned since she was four years old, and attributes it to 
a scare. 

In connection with these two cases, it is an interesting 
etiological factor to know that the mother is antimetropic, 
being higlily myopic in the right eye (13 D.), exactly the 
same as the myopia in right eye of the myopic daughter with 
divergent squint, and is slightly hypermetropic in the left eye, 
about .50 to 1 D. The father is hypermetropic, as is also a 
younger sister. Neither father or mother ever squinted, and 



ILLUSTEATIVE CASES 285 

the mother never wore glasses till forty-three years of age, 
which I gave her for reading (see case, Chapter XI). The 
question is: Did one daughter inherit one eye of the mother, 
and the other daughter the other eye ? It is a striking coin- 
cidence, to say the least. The report of the case of the sec- 
ond daughter is as follows : — 

Ophthalmometer. — Astigmatism with the rule, .50 D., axis 
90° + or 180° — right eye ; astigmatism with the rule, .75 D.,^ 
90° + or 180° - left eye. 

Test cards and trial lenses. — 

R. V. =|-^:-|^W. + 1.50D. 

L. Y. = 1^ : 1^ W. + 1 D. + .25 D. cyl., 90°. 

Reads Jaeger No. 1 from 6 to 20 inches with the left eye, 
and at the same distance with the right, if the left is covered. 

Ophthalmoscojje. — H. 2 D. right eye ; H. 1.50 D. left eye. 

There is a marked inward and upward squint of the right 
eye (about 20° in and 5° up), and a slight inward squint of the 
left eye, about 10°. There has been a tenotomy of the left 
internal rectus some years ago, but the oculist refused to oper- 
ate on the right eye for fear of overeffect. 

Under atropine, this patient accepted + .50 D. more sphere 
than when without it. I ordered -f 1.50 D. right and + 1 D. 
+ .25 D. cyl., 90°, left eye, for constant wear. December T, 
I made a complete and thorough tenotomy of the right internal 
rectus. For the first few days there was a slight divergence. 
Glasses were left off. After one week the eyes were straight 
and the patient had single binocular vision. But after two 
weeks' time the left eye began to turn in. I ordered her to 
wear the glasses again constantly, and, although the glasses 
were worn most of the time (the patient taking them off when 
in the street, against my orders), and atropine (solution 4 gr. to 
5 1) was instilled once a day iji each eye, it continued to squint. 
After a month's use the mydriatic Avas discontinued. The left 



286 THE KEFRACTIOX OF THE EYE 

eve then turned inward 10°, as it was before the operation on 
the right, the right now being the e}Te she fixed with and used. 
February 3, almost two months after the operation on the 
right eye, I did a tenotomy of the left internal rectus. There 
was a decided diyergence immediately following, taking 15° 
prism, base in, to correct. This gradually diminished from 
day to day, the glass being left off, till at the end of two 
weeks it was entirely gone and the eye was perfectly straight. 

_ The glasses were now ordered to be worn, but, after one 
month, they were ordered discontinued permanently, as the 
right eye had a tendency to diyerge if the patient got yery 
tired or excited. I haye seen the patient within a few days 
(nearly fiye months after the operation), and the eyes are per- 
fectly straight, and binocular single A*ision is present, both for 
distance and near. "With the stereoscope she can put the bird 
in the cage, the rider on the horse, etc., with ease. 

Case CIV. Divergent stralismus right eye; ^lyoina of 
large araount each eye; Correction of myopia ivith glasses ; Tenot- 
omy of right external rectus^ ivith advancement of right internal 
rectus; Cif re. ^ October 10, 1895, M. C, aged twenty-two 
years, has been near-sighted since a small child, but the right 
eye did not turn outward tmtil she was fourteen years old. 
She wore glasses for a while, but they did not help her much. 

Ophthalmometer. — Astigmatism with the rule, .75 D., axis 
90° + or 180° — each eye, with slight irregular astigmatism 
each. 

Test cards and trial lenses. — 

R Y = -1-4- • -2iL \v —ion 

^' ^ ' — 200 • 50 '^ • ^-' ^' 

Reads Jaeger No. 4 at 9 inches, with— 8 D. right and — 6 
D. left. Single binocular vision is absent. 

Ophthalmoscope. — M. 13 D. right eye: 11 D. left eye. 
There is a posterior staph^doma in each eye. with choroidal 



ILLUSTKATIYE CASES 287 

changes in the right. Oblique illumination shows some very 
fine opacities in the cornea in each eye. Test under atropine 
resulted in the patient accepting the same glasses as when 
tested without the mydriatic. Ordered, — 12 D. right and 
— 10 D. left for distant vision, and — 8 D. right and — 6 D. 
left for near vision. 

October 17, I did a tenotomy of the right external rectus 
and advancement of the right internal rectus. This operation 
straightened the eye, and for about four months while under 
observation it remained straight. Binocular single vision was 
not secured. This case is a representative one of a typical 
class of cases, that is, of myopia with divergent strabismus. 
In such cases, the squint usually develops between the ages of 
twelve and twenty-five years, and not in early childhood, as 
does convergent strabismus. Glasses alone, as a rule, do not 
relieve it, and an operation must be resorted to in order to 
cure it. Moreover, a simple tenotomy of the antagonist (ex- 
ternal rectus), of the weak muscle (internal rectus), or even 
tenotomy of the associated antagonist (external rectus of the 
opposite eye), in conjunction, does not, as a rule, relieve it. A 
tenotomy of the external rectus and an advancement of the 
internal rectus of the squinting eye is the best procedure to 
follow, while the external rectus .of the non-squinting eye 
should not, as a rule, be operated upon. 

Case CV. Periodic convergent strabismus at the age of 
f orty -one ^ following a fixed squint of childhood; Never had glasses 
or operation; Simple hypermetropia ; Squint is non-comitant, 
though not paralytic ; Binocidar single vision for distance, hut not 
for near. — March 1, 1898, Mary H., aged forty-one, came to 
the clinic of Drs. Lewis and Van Fleet for readino- o-lasses, and 
was assigned to me to test. She gives a history of squinting 
at times with the left eye since a child. The left eye, when 
she was a young girl, turned in all the time, but she '' outgreAV 
it," and it rarely turns in now — only when excited or strain- 



288 THE REFEACTIOX OF THE EYE 

ing the eyes for close work. The eyes are perfectly straight 
now. In making the routine test for squint, the following 
peculiarity in her case was brought out : With the screen test, 
first covering one eye and then the other, and having the, 
patient look at a pencil held in front of her, it was discovered 
that when the amblyopic eye — the left, the one that had 
squinted in childhood — was covered, and the object fixed 
with the good eye (right), the left eye turned far in toward 
the nose. But, when the right or good eye was covered with 
a card, and the object fixed with the left eye, the right did not 
squint in or out, but remained directed toward the object, as 
shown both by looking at it back of the card and by it remain- 
ing still and fixed on the object when uncovered. If the 
object was held at twenty feet, no turning of either eye took 
place when covered or uncovered. Furthermore, with both 
eyes uncovered, no turning of the left eye took place. It is 
the only case of the kind that has ever come under my obser- 
vation, and I called the notice of Dr. Lewis and others to it. 

Ophthalmometer. — Astigmatism with the rule, .50 D., axis 
90°+ or 180° -each eye. 

Test cards and trial lenses. — 

^•^•= M • ff W. + 1.50D. 
L V — -^-^- ' -2-0- W 4- 3 D 

-^•^• — 200*100 ''^•^^ ^' 

Reads Jaeger No. 1 from 8 to 16 inches, with plus .50 D. 
added to the distance glasses. Ordered + 2 D. right and + 
3.50 D. left for reading. The patient has worn these glasses 
for more than eleven months with entire satisfaction. No 
distance glasses were given, as the patient did not feel the 
need of them and would not wear them. I had no desire to 
have her wear such glasses, since she had gone thus far in life 
without them ; however, she should have had glasses fitted 
when a child for constant wear. But no operation should have 
been done, for very likely it would have resulted in a divergent 



ILLUSTRATIVE CASES 289 

strabismus, since she " outgrew " or got over the convergent 
squint without any aid whatever. The case emphasizes the 
point in a negative way that we should not be in too much of 
a hurry in operating on young children with convergent squint. 
Another case in point is the following. 

Case CVI. Periodic convergent strabismus in cTiildJiood 
recovered from at the age of thirty-one without glasses or opera- 
tion; Large amount of compound hypermetropic astigmatism in 
each eye^ luith marked amblyopia in the left eye; Asihenoj)ia ; 
Relief with glasses. — February 3, 1899, Miss P. A. B., aged 
thirty-one years, consulted me because of painful vision. After 
she reads for a while the eyes get tired, and she has to stop and 
cover them for a few moments before she can go on again. 
She has never worn a glass, though when she was young the 
left eye turned in at times, but by voluntary effort on her part 
she could prevent the eye from turning. Her parents called 
her attention to it at first, and she could feel it turn, but by 
constantly being reminded of it, and with persistent effort, she 
prevented the eye from turning permanently. After reaching 
the age of twenty-five she had but little trouble to keep it 
straight, and now the eye does not turn at all unless under 
great strain. 

Ophthalmometer. — Astigmatism with the rule, 8 D., axis 
45° H- or 135° — right eye ; astigmatism against the rule, 3D., 
axis 135° -{- or 45° - left eye. 

Test cards and trial lenses. — 
R. V. = -5;2_p_ . 2^ w. + 1.50 D. + 3.25 D. cyh, 45°. 
L- V. = ^2^ : ^^%^Y. + 3.50 D. + 3.25 D. cyh, 135°. 

Reads Jaeger No. 1 from 6 to 16 inches. She has single 
binocular vision. Ad. 12°, ab. 3°, sur. R. 5°, L. 2°. 

Ophthalmoscope.— Yl.2.bOT>. at 45° and H. G D. at 135° 
right eye ; H. 4.50 D. at 135° and H. 8 D. at 45° left eye. 

A second test agreed essentially Avith the lirst, and the 



290 THE REFRACTION^ OF THE EYE 

glasses were ordered. The patient obtained immediate relief 
from her asthenopia, the tendency of the left eye to turn 
inward disappeared, and she could read without discomfort. 
The ophthalmometer in pointing out the slanting axes at 
which the astigmatic glasses had to be worn in this case was of 
the greatest assistance, especially in the left or amblyopic eye. 

Illustrative Cases of Muscular Insufficiency 

In this class of cases, extreme examples of which are for- 
tunately rare, the object of prime importance in all of them is 
an accurate fitting and adjustment of glasses. This procedure 
alone, when accurately done, will relieve the great majority of 
cases of muscular insufficiencies, especially if tonics are given, 
and an outdoor exercise can be followed for a few hours each 
day for a month or two. 

In the most severe cases, which finally develop into squint, 
sometimes tenotomy of the muscles has to be done in order to 
get relief from the deformity, just as in other cases of squint. 

Case CVII. Insufficiency of the internal recti muscles; 
simple Jiypermetropia of small amount ; Asthenopia ; Correction 
of refractive error ; Tonics ; Relief . — February 27, 1897, P. E. R., 
aged thirty-four years, in good health, has complained for a 
number of months of a dull and drowsy feeling, also that the 
eyes were weak and ran water when he used them much. He 
has a slight conjunctivitis, but not enough to cause his trouble. 
Ophthalmometer. — Astigmatism with the rule, .50 D., axis 
90° -t- or 180° - each eye. 

Test cards and trial lenses. — 

R. V. = f^-:|^W. +.50D. 

L. V. =|^-:|-^W. +.50D. 

Reads Jaeger No. 1 from 6 to 18 inches. Ad. 5°, ab. 3°, 
sur. R. and L. 2°. 

Ophthalmoscope. — H. ID. in each eye. 



ILLUSTRATIVE CASES 291 

An astringent wash was ordered for the conjunctivitis, and 
strychnine sulphate, gr. -g^Q-, as a tonic, three times a day. 

Ten days later a second test was made. The ophthalmom- 
eter and ophthalmoscope accorded with the first test, and the 
patient accepted + .50 D. sphere in each eye, as before. Ad. 7°, 
ab. 3°, sur. R. and L. 2°. Ordered + .50 D. sphere for reading ; 
and the eye wash and strychnine were continued. 

Within six weeks' time this patient was entirely free from 
his asthenopic symptoms, the muscle insufficiency had dis- 
appeared, and the patient was comfortable. After two months' 
treatment I ordered the strychnine stopped, but advised a little 
outdoor exercise each day. It is now over two years since I 
first saw him, and he remains free from eye trouble. If he 
feels " run down " at any time I have him take the tonic of 
strychnine for four to six weeks, but this has been necessary 
but twice during the period stated. 

Case CVIII. Marked msufficieney of the internal recti; 
Simple liypermetropia of moderate amount ; Asthenopia; Correc- 
tion of the refractive error; Tonics; Relief. — April 17, 1897, 
Miss L. W. P., aged twenty-one years, in fairly good health, 
but is hard worked as a stenographer. She has at times had 
" attacks," in which she would lose consciousness, and during* 
some of these attacks would have involuntary movements of 
the bowels and bladder, but never bit her tongue. She is 
rather nervous. She has worn glasses for two and one-half 
years, but they have not been satisfactory. There is great 
blurring of images at times, and much pain in the eyes and 
head after using the eyes for a long while. 

Ophthalmometer. — Astigmatism with the rule, .50 D., axis 
90° + or 180° - each eye. 

Test cards and t7'ial lenses. — 

R.V. = |^:fJW. -f-l.oOD. 



292 THE REFPxACTIOX OF THE EYE • 

Reads Jaeger Xo. 1 from 6 to 18 inches. 

OiyJitlial mo scope. — H. 2 D. each. Ad. 6°, ab. 7°, sur. R. 
and L. 2°. Ordered strychnine sulphate, gr. -g^j. three times 
a day. Three days later the patient accepted exactly the same 
glasses as at the first test, and they were ordered. The ad. was 
7°, ab. 7°, sur. R. and L. 2°. At the end of one week the patient 
was perfectly comfortable, and in two weeks the muscle test 
was as follows : ad. 9^ ab. 7°, sur. R. and L. 2°. In four 
weeks: ad. 12°, ab. 7°, sur. R. and L. 2"^. After two months the 
strychnine was stopped. These glasses were worn with com- 
fort until December, 1898, almost two years, when she returned, 
complaining of pain in the left eye. On testing the patient's 
eyes the following conditions were found : — 

Ophthalmometer. — Astigmatism with the rule, .50 D., axis 
45° + or 135° — right eye; astigmatism against the rule, .50 
D., 135° + or 45° - left eye. 

Te8t cards and tried lenses. — 

R. V. = |A _ : 14 ^\. +2 D. 4- .25 D. cyl., 45°. 
L. V. = y - : ff W. + 1.75 D. 4- .25 D. cyL, 135°. 

Reads Jaeger Xo. 1 from 6 to 18 inches. 

Ophthalmoscope. — H. 2D. each. Ad. 7°, ab. 7°, siu\ R. 
and L. 1°. 

Three days later a second test was made, the patient 
accepted the same glasses, and they were ordered. Str^xhnine 
sulphate, gr. gL, was ordered to be taken three times a day for 
a few weeks. It has been four months since these last glasses 
were ordered ; the patient, whom I see from time to time, 
tells me she is without any pain at all, and can work for long 
hours. 

The patient has had none of her '• attacks " since being 
Tinder my care. 

The other interesting feature in this case to me. besides the 



ILLUSTRATIVE CASES 293 

insufficiency of the muscles, was the change in the shape of the 
cornea. When I first saw her, the ophthalmometer showed 
astigmatism with the rule, .50 D., axis 90° + or 180° — . The 
patient accepted no cylindrical glass. About two years later 
the instrument showed astigmatism of .50 D., but the axis was 
at 45° in the right eye and at 135° in the left. This was a 
change in the axis of 45° in each eye. Furthermore, the 
patient accepted + .25 D. cyl., 45° right, and + .25 D. cyl., 
135° left, in addition to the spherical glass. 

In this case, when I first saw her, the abduction actually 
exceeded the adduction ; yet, with a proper correction of the 
refractive error, and by the aid of tonics, the patient was not 
only able to pursue her work with comfort, but was cured of 
what appeared to be petit mal. 

Case CIX. Insufficiency of the internal recti muscles ; 
Simple hypermetropic astigmatism; Asthenopia; Correction of 
the refractive error ; Relief. — October 7, 1893, K. E. H., aged- 
twenty-one years, student, never very strong, has been troubled 
with his eyes since about twelve years of age. Was fitted to 
glasses in the Manhattan Eye and Ear Hospital, when seven 
years of age, and was given + 1 D. sphere combined with 1° 
prism, base in, for each eye for reading. These glasses helped 
him very much the first year, but have not been comfortable 
since then, though they were much better than no glasses. He 
comes to the clinic again on account of pains in the eyes and 
headaches. 

Ophthalmometer. — Astigmatism with the rule, 1 D., axis 
90° H- or 180° - right eye ; 1.25 D., axis 90° -j- or 180° - left 
eye. 

Test cards and trial lenses. — 

R. V. = f - : f + w. + .50 D. cyl., 90°. 
L- V. = ff - : |g + W. -{- .75 D. cyl., 90°. 



294 THE REFRACTION OF THE EYE 

Reads Jaeger No. 1 from 4 to 20 inches. Ad. 10°, ab. 8°, 
sur. R. and L. 2°. 

Ophthalmoscope. — B.. .50 D. at 90° and H. 1 D. at 180° 
each. 

A second test, made very carefully as to the astigmatism, 
resulted in the patient accepting the same glasses exactly as at 
the first test. They were ordered. The patient reported at 
the clinic weekly, for several weeks, as I wished to see if the 
simple cylinders would relieve him entirely. He said that 
they gave him relief from the pain in th6 eyes and his head- 
aches, and were much more comfortable than the spherical 
glasses and prisms. The internal recti gained in strength also, 
while the external remained as they were at first. 

Case CX. Insufficiency of all the recti muscles ; Relatively^ 
the external recti were weaker than the others^ as an homonymous 
diplopia was present at times ; Compound hypermetropic astigma- 
tism ; Correction of refractive error ; Tonics ; Relief. — Novem- 
ber 20, 1894, Sadie G., aged fourteen years, in good health, 
came to the clinic of Drs. Lewis and Van Fleet, and was 
assigned to me for examination. She complains of seeing 
double at times, but otherwise has had very little trouble with 
her eyes. For the last few weeks the lids have been somewhat 
inflamed, and stick together in the morning. 

Ophthalmometer. — Astigmatism with the rule, 1 D., axis 
90° -f or 180° - each eye. 

Test cards and trial lenses. — 

R. V. = f§ : fl- W. + .50 D. cyl., 90°. 
L. V. = 1^ : ff W. -h .50 D. cyl., 90°. 

Reads Jaeger No. 1 from 5 to 15 inches. A 1° prism gives 
diplopia in every direction, and over whatever muscle the apex 
is placed. The fact, however, that the patient has occasional 



ILLUSTRATIVE CASES 295 

homonymous diplopia, especially when looking at near objects, 
would indicate a relative weakness of the external recti 
muscles. 

Ophthalmoscope, — H. .50 D. at 90° and H. 1 D. at 180° in 
each eye. 

A mild astringent wash was ordered for the lids and strych- 
nine sulphate, gr. g^^ three times a day, as a tonic. 

One week later, a second test was made. The ophthal- 
mometer and ophthalmoscope gave the same results as at the 
first test, and the patient again accepted simple cylindrical 
glasses, which were ordered. 

The muscles were in exactly the same condition as the 
week previous. The patient was instructed to wear the 
glasses constantly, to continue the tonic of strychnine, to take 
some outdoor exercise, and to report in one month. At the 
end of a month the patient had no dij)lopia, eyes comfortable, 
and she was feeling much better in every way. Ad. 4°, ab. 1°, 
sur. R. and L. 1°. The patient was ordered to report if the 
eyes troubled her again, but has not been seen since then. 

Case CXI. Insufficiency of all of the recti muscles ; Trouble- 
some homonymous diplopia; Compound hypermetropic astigma- 
tism; Asthenopia; Dizziness; Correction of refractive error ; Tonic 
given, and less work ordered ; Relief. — December 26, 1893, Miss 
B. C, aged thirteen years, came to the clinic of Drs. Lewis 
and Van Fleet, complaining of dizziness and of seeing double 
at times. The patient has always enjoyed good health, and her 
father and mother are living and in good health. She has one 
brother and three sisters, all younger than herself, and with no 
eye troubles of any kind. The patient is very studious, goes 
to school during the day and studies till eleven o'clock at 
night, besides doing outside reading. 

Ophthalmometer. — Astigmatism with the rule, 2 D., axis 
90° + or 180° - right eye ; 2.75 D., axis 90° + or 180° - left 
eye. 



296 THE REFRACTION OF THE EYE 

Test cards and trial lenses. — 

R. V. = f^ : 1^ W. + 1.25 D. cyl., 90°. 
L-^-=A'o=MW. + 2 D. cyl., 90°. 

Heads Jaeger No. 1 from 6 to 14 inches. A 1° prism gives 
diplopia in all directions, that is, when the apex is placed over 
any one of the recti mnscles it causes diplopia. 

The diplopia that the patient complains of, and which can 
be produced at will by putting a red glass in front of one eye, 
is homonymous most of the time, but occasionally is crossed, 
especially when the patient first looks at near objects. 

Ophthalmoscope.— li, 1 D. at 90° and H. 3 D. at 180° 
right eye ; H. 2 D. at 90° and H. 4 D. at 180° left eye. 

Ordered strychnine sulphate, gr. gL.^ taken three times a 
day, and to do less work with the eyes ; also an hour's walk 
each day. Four days later a second test was made. 

Ophthalmometer. — Astigmatism with the rule, 1.75 D., 
axis 90° + or 180 °- right eye ; 2.50 D., axis 90° + or 180° - 
left eye. 

Test cards and trial lenses. — 

R. V. = 1^ : |§- W. + 15 D. 4- 1.25 D. cyl., 90°. 
L. V. = 1^ : 1^ W. + 75 D. + 2 D. cyl., 90°. 

Reads Jaeger No. 1 from 6 to 15 inches. The ophthal- 
moscope showed the same condition as at the first test. A 
third test, two days later, resulted in the patient accepting 
the same glass as that accepted on the second, and the glasses 
were ordered for constant wear ; the tonic was continued, 
and the patient admonished not to use the eyes to the point 
of abuse as she had been doing. 

An immediate effect of the glasses was the relief of the 
diplopia and dizziness. If she took the glasses off, diplopia 
would manifest itself, but while she kept them on she had 
relief. 



ILLUSTRATIVE CASES 297 

These two cases just reported show that muscular insuffi- 
ciency of marked degree, and even when attended with occa- 
sional diplopia, may be relieved by glasses and tonics, without 
operative interference. Sometimes, however, it will not yield 
to this simple procedure, and an operation has to be resorted 
to, as shown by the following case. 

Case CXII. Insufficiency of the internal recti; Simple 
hypermetropic astigmatism ; Occasional crossed diplopia ; Dizzi- 
ness ; Marked asthenopia; Correction of refractive error and 
tonics without relief ; Prisms added to glasses without reliefs hut 
with the development of divergent squint; Operation; Relief. — 
Miss Celia L., aged twenty years, in good health, consulted me 
first on September 12, 1893, on account of pains in the eyes, 
headaches, dizziness, and because she saw double occasionally. 
She was fitted with glasses two years ago, which were com- 
fortable until she began to sew on fine work about two months 
ago. 

Ophthalmometer. — Astigmatism with the rule, 2.75 D., 
axis 120° + or 30° - right eye ; 2.75 D., axis 90° + or 180° - 
left eye. 

Test cards and trial lenses. — 

R. y. = 2^ + : 20 + ^y. _|. 2.25 D. cyl., 120°. 
L. V. = 1^ - : 1^ - W. + 2.25 D. cyl., 90°. 

Reads Jaeger No. 1 from 6 to 18 inches. Ad. 5°, ab. 7°, 
sur. R. and L. 1°. 

Ophthalmoscope. —^m. at 120° and H. 2 D. at 30° right 
eye ; Em. at 90° and H. 2 D. at 180° left eye. 

The patient has been wearing for a year + 2 D. cyl., 120°, 
right, and + 2 D. cyl., 80°, left; and these glasses give her 
about as good vision as the glasses she now accepts. Ordered 
tonic of strychnine, and a mild astringent wash, for a slight 
conjunctivitis that is present. 

Three weeks later the patient returned, not improved, but 



298 THE EEFRACTION OF THE EYE 

worse as regards tlie insufficiency. The glasses could not be 
improved upon: ad. 1°, ab. 9°, sur. R. and L. 2°. She has 
great pain in using the eyes, and the diplopia is more trouble- 
some than ever. With a red glass in front of one e^'e, the 
diplopia is constant, vertical, and crossed. Prism 1°, base 
down, and prism 5°, base inward, in front of left eye, corrects 
same. These prisms, divided between the two eyes, were 
added to her glasses, and for four months she was very com- 
fortable ; but, on February 14, 1894, she returned, complain- 
ing of her old symptoms, especially of the diplopia, which was 
constant. A divergent strabismus of between 5° and 10° was 
present in the right eye. 

An operation was advised and performed — a complete tenot- 
omy of the right external rectus nluscle. A very small opening 
was made in the conjunctiva, and then in the capsule of Tenon, 
being careful not to dissect up the capsule to any great extent, 
but just enough to pick up the tendon of the muscle, which 
was divided completely. 

At first there was over-correction, the eye turning inward 
too far by 15°, as shown by the prism which it took to correct 
a homonymous diplopia. Ordered to wear her glasses without 
prisms. In one month's time the eyes were perfectly straight, 
ad. 15°, ab. 6°, sur. R. and L. 2°, single binocular vision. 
The patient was entirely comfortable, and able to pursue her 
vocation as a seamstress. 

The angle alpha in this case was positive, but very narrow, 
2° ; and this may, in a measure, account for the insufficiency 
of the internal recti muscles, developing into a divergent stra- 
bismus. 

This patient is still under observation, and she is comfort- 
able. The following case is similar to the present one, but no 
prism was tried before the operation was done. 

Case CXIII. Insufficiency of the internal recti muscles ; 
Occasional diplopia for the near point ; Hypermetropia of small 



ILLUSTRATIVE CASES 299 

amount^ with slight astigmatism in the left eye ; Marked astheno- 
pia ; Glasses^ tonics^ prism exercises^ open-air exercises^ and rest^ 
all fail to relieve ; Tenotomy of the right external rectus^ followed 
in two and one-half years with tenotomy of the left external rectus^ 
effect a cure. — June 1, 1896, C. H. M., aged seventeen years, 
in only fairly good health ; his vitality is much reduced on 
account of long hours of study and sexual excesses. He has 
passed through many hands, — sixteen in all, — has v7orn 
glasses and taken tonics, but without relief from headaches and 
pains in the eyes, of which he complains. The headaches are 
present even in the morning, and are intensified by using the 
eyes. Print doubles after using the eyes for a little while. If 
he cannot get relief, he says he must give up his studies. He 
comes from a healthy family, and none of them, except himself, 
are troubled with their eyes. 

Ophthalmometer. — Astigmatism with the rule, .50 D., axis 
90° + or 180° - each eye. 

Test cards and trial lenses. — 

L- V. = 1-2- : |o _ w. + .25 D. cyl., 90°. 

Reads Jaeger No. 1 from 6 to 15 inches. Ad. 10°, ab. 9°, 
sur. R. and L. 3°. 

Ophthalmoscope. — H. 1.50 D. each eye. 

Ordered strychnine sulphate, gr. -gL, three times a day, the 
patient to study less, to desist from his excesses, and to take 
more outdoor exercise. He has been riding the bic3Tle con- 
siderably already. 

Three days later, a second test was made, and but little 
change in the condition of the eyes was found. Ordered : 
+ .50 D. right, and + .25 D. cyl., 90°, left, to be worn con- 
stantly, and the other treatment continued. Ten days later, 
the eyes not improving, the strychnine was increased to gT. ^V, 
three times a day, the patient being cautioned as to the physio- 



300 THE REFRACTION OF THE EYE 

logical effect of tlie strychnine. Prism exercises were ordered 
in addition to other treatment, although I have little faith in 
such exercises, and would not now advise them. 

Six weeks later, the patient getting no better, but worse, — 
ad. 9°, ab. 10°, sur. R. and L. 3°, — I advised tenotomy of the 
right external rectus, and this was performed August 14. Ho- 
monymous diplopia immediately following, from over-correc- 
tion, required prism 10°, base out, to correct. Eleven days 
later, the diplopia disappeared, ad. 16°, ab. 4°, sur. R. and L. 2°. 
September 21, ad. 14°, ab. 6°, sur. R. and L. 2°, eyes perfectly 
comfortable, and he resumed his studies. 

February 16, 1897. He has trouble again with his eyes, 
from too close application to studies and from sexual excesses. 
Tonics and rest relieved him. 

January 4, 1898. Patient returns, complaining that he 
does not feel well, has had some trouble with his heart, head- 
aches, general lassitude, and eyes suffer, with general depressed 
condition. He continues to dissipate from time to time. His 
old glasses cannot be improved upon. The vision in each eye 
= |-a ; ad. 10°, ab. 8°, sur. R. and L. 2°. I told the patient I 
could do no more for him unless he obeyed instructions and 
stopped dissipating. He went to another oculist, who put him 
under a mydriatic, and gave him -|- 1.50 D. each eye, full cor- 
rection. These glasses did not give him relief. The adduc- 
tion was already too weak, and to put full correction of his 
hypermetropia on him simply made it weaker ; and when he 
came to me again, on December 20, 1898, he was complaining 
of diplopia, much headache, and pains in the eyes. Ad. 8°, 
ab. 9°, sur. R. and L. 2°. Advised and performed a tenotomy 
of the left external rectus. A decided convergence followed, 
requiring prism 20°, base out, to correct it. Glasses were left 
off. The convergence gradually diminished, as it had after 
the operation on the right eye ; and, by January 25, 1899, — 
about five weeks, — parallelism existed; ad. 20, ab. 2°, sur. R. 



ILLUSTRATIVE CASES 301 

and L. 2°. February 10, ad. 16°, ab. 5°, sur. R. and L. 2°. 
The patient is perfectly comfortable, and able to use the first 
glasses given him. 

It has been five months since the last operation ; the patient 
has no asthenopia, is comfortable, and in school. 

Case CXIV. Insufficiency of the internal recti; Asthenopia; 
^Photophobia ; Neuralgia ; Emmetropia ; Reading glasses ordered; 
Tonics ; Improvement in the eyes^ hut not entire relief from asthe- 
nopic symptoms. — March 25, 1898, Miss F. M., aged forty-three 
years, in delicate health, complains that her eyes have troubled 
her for a year. She thinks it has something to do with an 
ovarian neuralgia (right side) from which she has suffered for 
the last year. The pain begins in the eyes first, as a rule, but 
often it is just the reverse. She has severe headaches, especially 
in the back part of her head. 

For the last three weeks she has suffered greatly from severe 
pain in the eyes and from photophobia, and has been compelled 
to wear blue glasses to keep the light out of her eyes. 

Ophthalmometer. — Astigmatism with the rule, .50 D., axis 
90° + or 180° - each eye. 

Test cards and trial 



R. V. = 1^ -f : not improved. 
L. y. = 1^ + : not improved. 

Reads Jaeger No. 1 from 8 to 20 inches, with + .50 D. 

Ad. 10°, ab. 8°, sur. R. and L. 2°. 

Ophthalmoscope. — Emmetropia each. Some congestion of 
the fundus in each eye, but no lesion. 

Ordered + .50 D. for each eye for reading. Under a tonic 
of strychnine and arsenic, general hygiene and rest, she was 
much improved in general health ; and her ovarian neuralgia 
and also the asthenopia and photophobia were helped, but not 
entirely relieved. However, she would have periods when all 



302 THE REFRACTION OF THE EYE 

of her old symptoms would reappear. Her adduction was in- 
creased to 14°, while ab. and sur. remained as before. 

In such a case as this it would have been futile to cut 
the ocular muscles, for the asthenopia and ovarian trouble 
were likely both due to a common cause. At any rate, when 
she was feeling well, generally, the eyes gave her little or no 
trouble, indicating clearly that the eye trouble was not local, 
but due to a general debility. 

Case CXV. Insufficie7icy of the internal recti; Small amount 
of hyper metropia ; Presbyopia; Asthenopia; Correction for near 
work; Tonics; Exercise; Relief. — December 29, 1896, C. H., 
Esq., aged fifty years, in good health, but uses his eyes ex- 
cessively. He complains of pain in the eyes and of redness of 
the lids after using the eyes in the evening. He has had 
rheumatism in mild attacks for the last few years. 

Ophthalmometer. — Astigmatism with the rule, .50 D., axis 
90° -f or 180° - both. 

Test cards and trial lenses. — 

R. V. =||:|^ + W. + .50D. 
I-V. =fM^+W. + .50D. 

Reads Jaeger No. 1 from 8 to 24 inches, with + 3 D. sphere. 
Ad. 10°, ab. 8°, sur. R. and L. 2°. 

Ophthalmoscope. — H. .50 D. each eye. 

One day later, a second test was made, and the patient 
accepted the same glasses as at the first test. Ordered + 3 D. 
each eye for reading. Also ordered a tonic of strychnine and 
open-air exercise. After three months' treatment, adduction 15°, 
ab. 7°, sur. R. and L. 3°. The patient is entirely comfortable 
and able to use his eyes for long hours. The strychnine was 
stopped. I saw this patient a year later, and again two years 
later. He accepted no increase in presbyoj^ic glass ; ad. 14°,^ 
ab. 6°, sur. R. and L. 2°; was still entirely comfortable, but 
as he was passing through the city, stopped to let me see him. 



i 



ILLUSTRATIVE CASES 303 

Case CXVI. Insufficiency of the internal recti; Mixed 
astigmatism in one eye^ and compound hypermetropic astigma- 
tism in the other; Occasional diplopia at the near point; Severe 
headaches ; Has had a number of graduated tenotomies ; Correc- 
tion of refractive error; Tonics; Relief. — January 9, 1894, 
W. J. C, aged twenty years, in fairly good health, a close 
student, consulted me on account of severe headaches, and 
because he saw double for near work after using the eyes for 
any considerable time. He is one of the unfortunates who has 
been subjected to several, he does not know just how many, 
graduated tenotomies. From moderate headaches and no 
diplopia before the operations, he now has very severe head- 
aches and frequently diplopia for the near point. 

Ophthalmometer. — Astigmatism with the rule, .50 D., axis 
105° + or 15° - right eye ; with the rule, 2.25 D., axis 105° + 
or 15° — left eye. 

Test cards and trial lenses. — 

^' ^- = I* • ff W. -f- .25 D. cyl., 105°. 

L. V. = J^ : 1^ W. + 1.25 D. cyl., 105° - .75 D. cyl., 15°. 

Reads Jaeger No. 1 from 4 to 15 inches. Ad. 2°, ab. 6°, 
sur. R. and L. 1°. 

Ophthalmoscope. — H. .50 D. right eye; H. 1 D. at 15° 
and M. 1 D. at 105° left eye. 

Ordered strychnine sulphate in increasing doses, and rest 
and exercise for a few days. 

Second test : the ophthalmometer gave the same readings 
as at the first test. 

Test cards and trial lenses, — 

R. V. =||:ffW. + .25 D. cyl., 105°., 

L. V. = 1^ : |g W. + 1 D. cyl., 105° - .50 D. cyl., 15°. 

Reads Jaeger No. 1 from 4 to 17 inches. Ad. 4°, ab. G°, 
sur. R. and L. 2°. 



304 THE REFRACTION OF THE EYE 

On a tliird test, the patient accepted exactly the same 
glasses as at the second, and they were ordered. The strych- 
nine, gr. g^Q, was given three times a day, and the patient 
directed to take some outdoor exercise each day. Within 
three weeks' time this patient's adduction exceeded his abduc- 
tion (ad. 7°, ah. 6°), his headaches and diplopia were gone, and 
he was able to use his eyes with comfort. The strychnine was 
continued for two months, when adduction was 10°, ab. 6°, and 
sur. R. and L. 2°. 

May 2, 1896, over two years after I first saw him, the 
patient returned with headaches and pains in the eyes. On 
inquiring, I found that he had broken the right glass, and had 
a new one put in without an order. On examination, I found 
the optician had put a cylinder in the right eye, axis at 75°, 
instead of 105°, as it should have been. The refraction had 
changed slightly in the left eye, the patient now accepting 
-f- .75 D. cyl., 105°- 1 D. cyL, 15°. Ad. 7°, ab. 7°, sur. R. 
and L. 2°. 

I again placed the patient on a tonic of strychnine, gr. -^, 
three times a day, for two months. I have heard from this 
gentleman, from time to time, for two years after this last 
examination, and though at times, when very hard worked or 
not feeling well, he has some pain in the eyes, he has no diplo- 
pia, and, as a rule, is comfortable, and can pursue his calling as 
a minister. 

Case CXVII. Insufficiency of the interyial recti; Occasional 
diplopia; Asthenopia ; Hypermetropia and Presbyopia; Reading 
glasses; Tonics; Relief. — November 26, 1896, Dr. D. L. H., 
aged forty-three years, in good health, has worn glasses for the 
last eighteen years. He complains of late that when he uses 
the eyes for any considerable time he gets pains in the back of 
the head and in the eyes. 

Ophthalmometer. — Astigmatism with the rule, .50 D., 90° 
-f- 180°- right eye ; with the rule, .25 D., 90° + 180°- left eye. 



ILLUSTRATIVE CASES 305 

Test cards and trial lenses. — 

^' ^' = U : f f W. + 75 D. 
L. y. = 1^ : f f W. + 75 D. 

Reads Jaeger No. 1 from 8 to 16 inches, with + 1.50 D. 
sphere in each. Ad. 10°, ab. 9°, sur. R. and L. 3°. If the 
patient does not fix his attention closely on objects, one eye 
will at times diverge ; but by effort he can overcome this. 
Ordered + 1.50 D. sphere, each eye, for reading, but discon- 
tinued his distance glasses. Strychnine was given in increas- 
ing doses till physiological effect was obtained. The patient 
got almost immediate relief. I wrote to the doctor two years 
later for a report of his case, and his reply is here given. 

"Dear Doctor Davis, — 

"Yours, relative to the condition of my eyes, is received. My eyes re- 
mained about the same for another year, when, on account of increased irrita- 
bility, I increased strength of glass from 1.50 D. to 1.75 D., which gives me 

absolute relief to the present time. ,, rr,, ^ . 

*' Thankmg you, etc., 

"D. L. H." 

The muscular insufficiency in this case was so marked that 
a periodical squint was present ; yet, with the correct glass for 
reading and tonics, he was cured. 

Case CXYIII. Insufficiency of the internal recti made 
worse hy wearing strong prisms^ bases in; Incapacitated for work 
on account of the great pain m the eyes and head; Compound 
myopic astigmatism; Mild trachoma; By taking off the prisms 
and giving the proper glasses^ the patient got entire relief., and was 
able to resume his professional callirig, that of a lawyer. — Octo- 
ber 1, 1898, H. A. T., Esq., aged thirty-six, in good health, 
except for his eyes, which have given him trouble for the last 
eighteen years. Has had a more or less severe inflammation of 
the lids for that time. His chief trouble, however, has been 



306 THE REFKACTIOIs^ OF THE EYE 

from a weakness of the eyes and inability to use them for any 
considerable length of time without great pain in them and 
severe headaches. Has consulted a number of oculists, and has 
tried many kinds of glasses, without much relief. In fact, he 
had to give up his profession on account of his eyes, because, 
after reading for a short time, the pain in his eyes would 
become unbearable. 

He has worn for the last two 5"ears — 1.50 D. —1.50 D. 
cyl., 170° right, and -2 D. -ID. cyl., 180° left, combined with 
5° prisms, bases in. These glasses gave him partial relief at 
first, but for the last year he thinks the eyes have been made 
worse. But as no other glasses — of which he had many 
pairs, plus, minus, with prisms and without — had given him 
any relief, he held to these until forced to try something else. 
I treated the eyelids for three months before testing for 
glasses, as I wished to eliminate that factor of the trouble. 
January 3, 1899, I made the first test. 

Ophthalmomete7\ — Astigmatism with the rule, 2.50 D., 
axis 80° -{- 170° - right eye ; with the rule, 2 D., axis 100° + 
or 10° - left eye. 

^' ^' = -iwo ''T%~^'- 1-25 D. - 2 D. cyl., 170°. 
L. V. = 2V0 : ff - W. - 1.25 D. - 2 D. cyl., 10°. 

Reads Jaeger No. 1 from 7 to 24 inches. Ad. 11°, ab. 13°, 
sur. R. 5°, L. 4°. Single binocular vision with effort. 

Ophthalmoscope.— M. 3 D. at 75° and M. 1 D. at 165° 
right eye ; M. 3 D. at 105° and 1.50 D. at 15° left eye. 

Ordered prism exercises. 

January 9. Ophthalmometer and ophthalmoscope gave the 
same readings as at the first test. 

^' V. = ^¥0 ^ ft- W. - 1 D. - 2.25 D. cyl., 170°. 
L. V. = 2^0 • ft - W. - 1.25 D. - 1.50 D. cyl., 10°. 
Ad. 17°, ab. 10°, sur. R. 4°, and L 3°. 



ILLUSTRATIVE CASES 807 

January 18. A third test corresponded with the second. 

Since this patient had had so many glasses, and all unsatis- 
factory, I put him under the influence of a mydriatic (scopola- 
mine), and on January 27, tested him under it, as follows : — 

Ophthalmometer. — Astigmatism with the rule, 2.50 D., 
axis 80° + or 170° - right ; 1.50 D., axis 100° + or 10° - 
left eye. 

Test cards and trial lenses. — 

R. V. = 2Vo-MH- W-- .75 D. -2 D. cyl., 170°. 
L. V. = -2V_ : 1^ + w. - 1.25 D. - 1.25 D. cyl., 10°. 

Ad. 10°, ab. 10°, sur. R. 6°, L. 4°. 

Ophthalmoscope. —M. 3 D. at 75° and M. 1 D. at 165° 
right eye; M. 3 D. at 105° and M. 1.50 D. 15° left eye. 

The retinoscope confirmed the ophthalmoscopic and sub- 
jective tests. The angle alpha was 3° in each eye. Ordered 
the glasses that were accepted under the mydriatic. 

February 3. Patient reports entire relief from, all asthe- 
nopic symptoms, is able to read for long hours without discom- 
fort, and is altogether happy. There is none of the drawing 
sensation in the eye as with the old glasses, and the weight of 
the glass itself is much less than the old heavy prismatic glasses. 

The old mistakes of over-correcting the spherical part of 
the error of refraction, and under-correcting the cylindrical 
part, had been committed in this case, and besides these errors, 
the burdensome prisms of 5°, bases in, were added to the 
glasses. These prisms were gradually forcing the eye into a 
divergent squint. When I first saw the patient he had an 
adduction of only 11° and an abduction of 13°, and the patient 
^as under a constant strain in order to have single binocular 
vision. 

After two weeks' wearing of the glasses without prisms, 
the patient had ad. 18°, ab. 9°, sur. R. 1°, L 3°. He has been 
under observation for three months since the glasses were pre- 



308 THE REFRACTION OF THE EYE 

scribed, expresses himself as being entirely comfortable, and 
able to work with satisfaction for the first time in many years. 
While on this question of prisms, I may say that within a 
month I have removed a pair of prisms from a patient with 
a well-marked convergent strabismus, in which none of the 
refractive error had been corrected, the patient wearing a sim- 
ple prism 3°, base out, in front of each eye. No binocular 
single vision was present, and, of course, the prisms were 
worse than useless. Except in cases of paralytic squint, 
where they are to be recommended for temporary use until 
the patient has recovered under treatment, or by operation, 
prisms should not be given in strabismus cases. 



CHAPTER X 

ASTIGMATISM AFTER CATARACT EXTRACTION — TORIC LENSES 
— PERISCOPIC LENSES — DECENTERING OF LENSES — ILLUS- 
TRATIVE CASES 

As would be supposed, the aphakial or lensless eye, where 
the corneal astigmatism only has to be considered, is the ideal 
eye for the use of the ophthalmometer. Nevertheless, the nodal 
point is moved forward by the removal of the crystalline lens, 
and hence the cylinder being combined, almost without excep- 
tion, with a strong spherical glass, which must be worn one- 
half inch in front of the eye, the strength of the glass necessary 
for the correction of the astigmatism is rarely ever as great as 
that indicated by the ophthalmometer, even though the astig- 
matism is against the rule. The same law for reduction in 
strength holds in regard to prescribing spherical glasses after 
cataract extraction. For example, say the amount of hyper- 
metropia in an eye after cataract extraction is 11 D. Now, 
since there is no crystalline lens in such an eye, it Avould 
naturally seem that it would require a 4- 11 D. (3 J inch) lens 
to correct this error, and, as a matter of fact, it would, could 
the glass be worn in contact with the cornea. But since the 
ordinary wearing distance of a glass from the eye is 12 to 14 
mm., or about one-half inch, this moving forAvard of one-half 
inch perceptibly increases the strength of strong convex glasses, 
and, therefore, a reduction in strength must be made. In the 
present supposed example of 11 D. hypermetropia, instead of 
there being required a -t- 11 D. to correct it, a much weaker 
glass, when placed at the usual one-half inch wearing distance 
in front of the eye, will accomplish what is required. To be 
exact, it would require a glass of only ojin. + ] in. (^the Mn. 

309 



310 THE REFRACTIOX OF THE EYE 

being the distance in front of the eye that the glass is worn), 
which equals a four-inch focus glass ; and a four-inch focus 
glass equals 10 D. By which it is seen that one whole diopter 
is- deducted from the glass. 

This increase of the power of convex glasses, on account of 
this one-half inch (projection from the cornea) in front of the 
eyes, obtains in all other eyes, as well as in aphakia, but the 
glasses, as a rule, in other than aphakial eyes, are so weak that 
the slight displacement of one-half inch does not make a great 
difference in their strength. There are excejptional cases 
where it does, but they are rare. In cataract cases, how- 
ever, the glasses must be very strong, except when the eye 
has been strongly myopic before operation, and a slight change 
in the position of the glass in front of the cornea makes a great 
difference in the power of the glass, as shown above. To give 
another example, say the patient was hypermetropic 5 D. before 
the operation, and after the operation that he has a hyper- 
metropia of 16 D. It is evident that if a plus glass of 16 D. 
(2|- in. focus) could be worn in contact with the cornea it would 
correct the 16 D. of hypermetropia ; but, as it must be worn 
one-half inch in front of the eye, it must be reduced in strength. 
That is, it would require a glass of 2^ -f- J = S in. focus, which 
equals only 13 D., a decrease in strength of three diopters. 

The discrepancy in the reading of the ophthalmometer 
and the cylindrical glass accepted by the patient after cata- 
ract extraction is not because of an error in the reading of the 
instrument, but is to be ascribed chiefly to the great reduction in 
strength that has to be made in strong cylinders on account of 
the one-half inch distance at which they must be worn in front 
of the eye, especiall}' so when combined with strong spherical 
glasses. For example, if we have an astigmatism of 3 D. 
against the rule, 180° -h, and hypermetropia 10 D. ; the power 
of the glass to correct in the vertical meridian would be 13 D., 
and the horizontal meridian 10 D., if they could be worn in con- 



ASTIGMATISM AFTER CATARACT EXTRACTION" 311 

tact with the eye. But they are one-half inch in front of the 
eye. 13 D. = 3 in. focus, + j in. (in front of the eye) = 3J in. 
focus = 11 D. for the vertical meridian. For the horizontal 
meridian, 10 D. = 4 in., -f- |^ in. = 41 in. =9 0. The difference 
between 11 D. and 9 D., the glasses which respectively it re- 
quires to correct the vertical and horizontal meridians, on 
account of their position in front of the eye, is only 2D.; and, 
therefore, it would take but 2 D. cyl. to correct the 3 D. of 
corneal astigmatism. Again, take 6 D. of astigmatism, 180° +, 
with 10 D. of H. The vertical meridian would require 16 D. 
(21 in.) to correct it, if worn in contact with the eye-; 2^ in, 
H- 1^ in. = 3 in. = 13 D., which glass it really takes. The 
horizontal meridian would take 10 D. (4 in.); 4 + 1 = 41 in. 
= 9 D. Now, 13 D. — 9 D. = 4 D., the amount of cylinder, 
axis 180°, it takes to correct the 6 D. of corneal astigmatism. 
Carl Weiland, in writing on the subject, has this to say : — 
" Cases of aphakia are, therefore, the ideal field for kera- 
tometry, but owing to the high spheres usually necessary, there 
is a great difference between the correcting cylinder at 14 mm. 
from the eye and that in contact with the cornea, which latter, 
as we know, is given by Javal's instrument. The following 
table will show this at a glance, which is given for + 10 D. for 
far, and + 14 D. for reading. 

Table 



A 


A 


Full Cokrection 


A 


A 


Full Corbection 


+ 1 


+ 10 


+ 10 - .75 cyl. 


+ 1 


+ 14 


+ 14 - .60 cyl. 


- 1 


+ 10 


+ 10 + .73 cyl. 


- 1 


+ 14 


+ 14 + .05 cyl. 


-2 


+ 10 


+ 10 + 1.45 cyl. 


— 2 


+ 14 


+ 14 + 1.25 cyl. 


+ 2 


+ 10 


+ 10 - 1.50 cyl. 


+ 2 


+ 14 


+ 14 - 1.3 cyl. 


-3 


+ 10 


+ 10 + 2.1 cyl. 


-3 


+ 14 


+ 14 + 1.8 cyl. 


-4 


+ 10 


+ 10 + 2.8 cyl. 


- 4 


+ 14 


+ 14 + 2.5 cyl. 


-5 


+ 10 


+ 10 + 3.50 cyl. 


-5 


+ 14 


+ 14 + 3. 18 cyl. 


-6 


+ 10 


+ 10 + 4.1 cyl. 


-0 


+ 14 


+ 14 + 3.06 cyl. 



312 THE REFEACTIOX OF THE EYE 

" This shows conchisively the necessity of correcting in 
aphakia the keratomically determined cylinder for its position 
and for the coexisting axial condition, for even with a + 1 D. 
it amounts to .25 D. and more, while for an astigmatism of 
6 D. against the rule, it amounts to almost 2.50 D. At the 
same time, we observe that in the same individual the cyl- 
inder may have to be reduced perceptibly for reading. We 
also find that the numbers obtained by the keratometer are 
always too high, no matter whether the astigmatism is with or 
against the rule." ^ 

Theoretically, Weiland's position is correct, but in prac- 
tice, I have, more than once, seen the patient accept exactly 
what the instrument indicated, and even more. As a general 
thing, though, after cataract extraction, the patient will not 
accept as much cylindrical correction as indicated by the 
instrument. 

There is another feature of error in the ophthalmometer 
itself, in high degrees of astigmatism, 6 D. and over, — spheri- 
cal aberration. 

Thomas Reid, of Glasgow, in an article on the " Scope and 
Limits of Ophthalmometry," ^ calls attention to this point. He 
says : "With Javal's instrument with an image of 3 mm., and 
with the portable ophthalmometer (Reid's) with an image of 
2 mm., it is clear that from the spherical aberration the abso- 
lute size of the radius cannot be determined without reduction, 
as Leroy has done. Hence the necessity in these instruments 
of being adjusted to a spherical surface of known curvature, 
which at most expresses approximately the average curvature 
of the cornea. The results obtained by these instruments 
thus adjusted, although not theoretically perfect, will give 
the relative difference in degrees of corneal astigmatism 

1 "History and Principles of Keratometry," Knapp's Archives of Oj)hthal- 
mology, January, 1893. 

2 Annals of Ophthalmology, July, 1897, p. 456. 



ASTIGMATISM AFTER CATARACT EXTRACTION 313 

not greater than 5 D. with sufficient accuracy for practical 
purposes." 

In regard to the limit of the measuring power of the Javal- 
Schiotz ophthalmometer, especially its capacity to determine 
the relative difference of the refractive power of the two 
principal meridians, even in very high degrees of astigmatism, 
I may say the same restriction does not hold in the Javal- 
Schiotz instrument as in Reid's, and for the following reason : 
In both instruments the size of the image remains constant 
(3 mm. in Javal's, and 2 mm. in Reid's), but the size of the 
object varies. 

In Reid's instrument,^ the object measured is an iris dia- 
phragm, which can be made to vary in size. Now, " in this 
instrument, if we take the extremes of the index, = 12 mm. 
and = 16 mm., we find the corresponding diopters are 38.9 D. 
and 51.84 D." The difference between these two amounts, 
51.84 - 38.9 = 12.94, or about 13 D., the amount of the astig- 
matism (with the prism giving an image of 2 mm.) the instru- 
ment is capable of measuring. 

In Javal's instrument, the object is the distance between 
the inner edges of the mires. When both of these mires 
move at once, as in the instrument with the double movable 
mires, the size of the object can be made to change from 
10 cm. (100 mm.) to 40 cm. (400 mm.), the corresponding 
diopters to these numbers equal 20 D. and 80 D., respectively ; 
and the difference between 80 D. and 20 D. equals 60 D., the 
amount of astigmatism the instrument is capable of measur- 
ing. Of course it could show such a great difference in only 
a relative way, because the spherical aberration would be so 
great in such a case that the measurement would not be 
accurate, but only approximate. 

But it is the difference in the limit of the measuring power 
of the two instruments I wish to show. One has the capacity 

1 See description of Reid's Ophthalmometer in Appendix. 



314 THE REFRACTION OF THE EYE 

to measure 13 D. of astigmatism, while the other has the 
capacity to measure 60 D. While no such amount as 60 D. 
of astigmatism has ever been met with in practice, yet so 
large amount as 28 D. of astigmatism (and not after cataract 
extraction) has been seen and measured with the Javal oph- 
thalmometer, the patient accepting exactly the cylindrical 
glass indicated by the instrument. ^ 

Both the Javal and the Reid instruments may have the 
limit of their measuring power increased by taking out the 
usual birefractive prisms that come with them, and substituting 
prisms that give an image of only 1 to 1^ mm. in diameter. 
But ordinarily this is not required, and, moreover, it is not 
convenient. Except for scientific investigations, these extra 
prisms are not necessary, because both instruments are capable 
of measuring any case of astigmatism ordinarily met with ; 
for, except in cases of conical cornea and cases after cataract 
extraction, we rarely encounter an astigmatism of more than 

5 or 6 D. As far as the cases of conical cornea are concerned, 
fortunately they are rare, even they can be measured fairly 
accurately with the ophthalmometer. 

As for the astigmatism we meet with after cataract extrac- 
tion, while it is very great in some cases shortly after the ex- 
traction (two to three weeks), amounting in rare instances to 
as much as 22 D., this, as a rule, rapidly diminishes, till within 
six weeks to two months it rarely amounts to more than 5 or 

6 D., although in one case I have seen 12 D. of astigmatism 
remain permanently after extraction. So here again the oph- 
thalmometer is within its range of practical and accurate work. 

The latest investigations as to the amount of the astigma- 
tism after cataract extraction, both immediately (two weeks) 
after and several months later, are those of E. O. Pfingst, of 
Louisville, in Knapp's Archives of Ophthalmology.'^ In a series 

1 Dodd's case, cited in full farther on in this chapter. 

2 Bd. Vol. XXV, 1896, pp. 333-340. 



ASTIGMATISM AFTER CATARACT EXTRACTION 315 

of .fifty cases, lie found that the astigmatism, two weeks after 
operation, ranged from 1.75 D. with the rule to 22 D. against 
the rule ; that this rapidly diminished in amount for the next 
two to four weeks, then gradually diminished in amount for 
six months, after which, in the few cases which he had the 
opportunity of examining, he found no further change in the 
astigmatism. 

My own experience is similar to that of Pfingst and others 
who have made investigations in this class of cases. In pri- 
vate practice, and especially at the Manhattan Eye and Ear 
Hospital, where I was Interne for two years, I have made 
many observations with the ophthalmometer after cataract 
extractions. In some cases I have made the examination as 
early as the tenth day after the extraction. The first examina- 
tion usually showed a considerable amount of astigmatism 
against the rule (4 to 8 D.), while one showed as much as 
22 D. In a few cases, the astigmatism was with the rule, and 
amounted to as much as 4.50 D. in one case. 

In all of the cases that I have observed, the astigmatism 
has rapidly diminished in amount, till in no case, with two 
exceptions, six months after operation, did it amount to as 
much as 8 D., even where the astigmatism had been as much 
as 22 D. the first two weeks after operation. Eurthermore, 
in some cases of astigmatism against the rule of as much 
as 4 D. to 6 D. in amount, it vanished entirely; and, in some 
cases, an astigmatism of as much as 2 D. to 4 D. ao-ainst 
the rule changed to astigmatism with the rule. One case 
of 4.50 D. astigmatism with the rule diminished gradually 
to nothing, then an astigmatism of 1.50 D. against the rule 
developed. 

Complicated cases of cataract extraction are the ones that 
give rise to the largest amounts of astigmatism, incarceration 
of the iris in the whole length of the wound exerting the q-reat- 
est influence on the shape of the cornea, perhaps. Pringst's 



316 THE REFRACTION OF THE EYE 

case of 22 D. had this complication. The case of 22 D. 
observed by me occurred in a woman whom I operated on 
at the hospital, who fell over backward from a stool at 
the end of the first week after the operation, and pulled 
open the wound. This wound, in healing the second time, 
was grooved, and caused the very large amount of astigma- 
tism described. 

In his series of fifty cases, Pfingst stated that no case 
accepted more than 6 D. cylinder, although one case had as 
much as 22 D. astigmatism shortly after the operation. In 
the case of 22 D. of astigmatism against the rule observed by 
me, the patient would not accejDt more than 8 D. cylinder at 
the first test, and, afterward, when the astigmatism had been 
reduced to 5 D., the patient accepted 4 D. cylinder, in con- 
junction with the sphere for distance, and 3.50 D. cylinder 
with the sphere for reading. 

I have, however, seen one case where the patient accepted 
16 D. cylinder twenty-seven days after the operation. It was 
a case where incarceration of the iris in the whole length of 
the wound had taken place ; and still another case, in which 
11.50 D. cylinder, combined with a 4 D. sphere, was accepted 
for constant wear and with comfort. In the latter case, the 
wound pulled open twice during the healing process, and left 
a deep groove. Both of these cases are reported in full far- 
ther on in this chapter. 

One feature, of which Pfingst did not speak in his article, 
was the change in the axis of the astigmatism. I have found 
it to vary from five to thirty degrees in the first six weeks. 
This is to be accounted for by the healing process in the 
wound, the contraction of the scar, and, perhaps, to some 
extent, from the pressure of the lids during the healing. The 
axis of the astigmatism finally settled down to a definite place, 
just as the amount of the astigmatism did, after about six 
weeks' time. 



DECENTERING LENSES 317 

Owing to the change, both in the amount and the axis of 
the astigmatism, after cataract extraction, only temporary 
glasses should be given till the end of the second month after 
the operation, and it is safer to wait for five or six months 
before giving permanent glasses. 

The correct adjustment of glasses after cataract extraction, 
especially where both eyes have been operated upon, is an 
important matter. The adjustment for the distance or street 
glasses is quite different from that for the near or reading 
glasses. While the distance glasses should rest almost in the 
vertical plane, being very slightly tilted forward at the top to 
overcome spherical aberration, or a small amount of astigma- 
tism, if present, and should be centered with the pupils, the 
glasses for the reading distance are to be decentered toward 
the nose, and should be worn at a lower plane or level than the 
distance glasses, in order to allow the patient to look through 
the center of them. If this adjustment is not given to the 
near glasses, they act as prisms, bases out, and cause diplopia 
for the near point in the horizontal plane ; and, if not worn at 
a lower level than the distance glasses, they act as prisms, 
bases up, causing diplopia in the vertical plane — the combined 
action giving a crossed vertical diplopia. 

Holden has given a working formula for the decentering of 

lenses, as follows : — 

Px9 



M= 



D 



in which M is the number of millimeters of decentering that 
is required to give a lens, i>, of a certain power, to get the 
effect of a prism, P, of a certain number of degrees. As he 
says : " For the effect of any prism, multiply 8.7 mm. [practi- 
cally 9] by the number of that prism, and for any lens divide 
this product by the number of diopters of the lens.*' ^ 

1 Knapp's Archives of Ophthalmology, January, 1891, Vol. XX, pp. 1-25. 



318 THE REFRACTION OF THE EYE 

For example, say we have a lens of 6 D. in each eye, which 
we wish to decenter inwards, so as to act as prisms of 2°, 
bases in, 

6 

the number of millimeters of decentering required to give such 
a lens (6 D.) so as to act as a 2° prism. 

No displacement should be more than 7 mm. in each eye. 

The practice that is, I regret to say, sometimes followed, of 
putting a distance glass in one side of a reversible spectacle 
frame, and the reading glass in the other side, where but one 
eye has been operated upon, and causing the patient to reverse 
the frames when he wishes to change from distant to near 
vision, is an exceedingly bad one ; with such frames, it is 
impossible to give the correct adjustment, even with those that 
are reversed by turning on a vertical axis. I make it a rule, 
therefore, to give my cataract patients two pairs of glasses, one 
for the distance and one for the near point. 

Spherical and chromatic aberration are other troublesome fea- 
tures, that are coincidental to the strong glasses necessary 
after cataract extraction, and must not be lost sight of. I 
wish to speak especially of spherical or monochromatic aberra- 
tion, as it is sometimes called. 

William Harkness ^ has shown that " with a pupil four mm. 
in diameter the normal cornea produces monochromatic aberra- 
tion to the extent of 3^3 (1.2 D.); and as there is no confusion 
of images in the normal eye, it seems probable tliat the crystal- 
line lens exerts some compensating action. This suspicion is 
strengthened by the well-known fact that in aphakia the acute- 
ness of vision is nearly always improved by giving a certain 
inclination to the powerful convex glasses which are necessary." 

But the tilting of the strong convex glasses, necessary in 
cataract cases, serves not only to overcome this spherical 

1 Knapp's Archives of Ophthalmology, Bd. Vol. XII, p. 18. 



TILTING OF LENSES 319 

aberration spoken of by Harkness, but also for correcting in 
part or whole the astigmatism usually present after cataract 
extraction. Since this astigmatism is generally against the 
rule, that is, the vertical meridian, or one near it, is made 
flatter by the contraction of the scar, it can be easily corrected 
by rotating the strong spherical glass on the horizontal axis, or 
one near to it, the rotation being greater or less according to 
the astigmatism to be corrected. 

Dr. Green, of St. Louis, in a valuable and instructive paper, 
" An Elementary Discussion of some Cases of Centrical Refrac- 
tion through Tipped Spectacle Lenses," Transactions American 
Ophthalmological Society, Bd. Vol. V., 1888-90, pp. 690-717, 
discusses the subject of tilting of lenses, both spherical and 
cylindrical, at length, and at the close of the paper gives a 
table showing the effect of tilting lenses a certain number 
of degrees. I give his conclusions and the table. 

He says : " The change effected in the power of any lens by 
tipping may be summed up as follows : — 

" Every spherical lens is increased in power in all its merid- 
ians; the rate of increase and the actual increase being greatest 
in the vertical and the least in the horizontal meridian. A 
spherical lens is, therefore, also rendered astigmatic, and the 
excess of increase in power in the vertical meridian over that 
in the horizontal, for any given inclination, is the measure of 
the astigmatism. 

" Every convex or concave toric or sphero-cjdindrical lens is 
increased in power in all its meridians. When the two princi- 
pal meridians of the lens lie in the vertical and in the hori- 
zontal plane, respectively, the rate of increase in power is 
greatest in the vertical and least in the horizontal meridian ; 
and when the power of the untipped lens is greatest in the 
vertical meridian the actual increase is also greatest in the 
vertical meridian, and the astigmatism of the lens is increased. 
When, on the other hand, the power of the untipped lens is 



320 



THE REFRACTIO:Nr OF THE EYE 



greatest in the horizontal meridian, the astigmatism of the 
lens is at first diminished, and since the possible increase in 
power in the horizontal meridian is limited, there is always 
some value of cj) (the angle of tipping or inclination) at which 
the astigmatism of the lens is reduced to zero, and beyond 
which the direction of the meridians of greatest and least 
refraction is reversed. 

" In the case of a tipped piano-cylindrical (or other equiv- 
alent) lens, the greatest increase in power is in the meridian at 
right angles to the axis of the lens, the power of the lens in the 
meridian of the axis remaining at zero, the rate of increase, and 
also the actual increase in power is greatest when the axis of 
the untipped lens is horizontal, and is least when the axis of 
the untipped lens is vertical." 

The table that he gives shows the relative increase in 
power of a lens of given strength when tipped a certain num- 
ber of degrees, beginning at the vertical where it is tipped no 
or zero degrees, and gradually increased to 90°. However, 
I may say, that it is not practicable to tip any lens more 
than 20°. 

Table 



Angle of 
Tipping 


Sphere 


Cylinder or Equiv- 
alent, Axis 180° 


Cylinder or Equiv- 
alent, Axis 90° 


zero 


1. 


1. 


0. 


5° 


1.010 


1.002 


0.008 


10° 


1.012 


1.010 


0.032 


15^ 


1.097 


1.023 


0.074 


20° 


1.179 


1.041 


0.138 


25° 


1.297 


1.066 


0.231 


30° 


1.462 


1.096 


0.366 


35° 


1.689 


1.134 


0.555 


40° 


2.008 


1.178 


0.830 


45° 


2.464 


1.232 


1.232 


90° 


infinity 


2.236 


infinity 



TILTING OF LENSES 



321 



Ward A. Holden, in a most excellent and practical article 
on this subject,^ gives a working table for the tilting of lenses, 
wherein he not only shows the relative increase in power of 
a spherical lens by being tilted a certain number of degrees, 
but the actual increase in power of the lenses most commonly 
used after cataract extraction. I append the table, as it is 
of practical value. 

Table 



Spherical, Focus 
IN Inches 


Tilting 10° 


Tilting 15° . 


Tilting 20° 


4i 


■Tio + 


■5\- 


^ 


4 


Tio + 


^V + 


^v- 


H 


io - 


z\ + 


2V + 


H . 


■h - 


io- 


^v- 


3 


^ - 


io + 


^v + 


2| 


^ - 


^ + 


^ + 


^ 


i^ + 


i-.- 


tV 


n 


i, + 


■h 


^ + 



To give an example, say a spherical glass of 21 inch focus 
(16 D.), often given as a reading glass after cataract extrac- 
tion, is tipped forward 10°, it would increase its strength in 
the vertical meridian .50 D. ; if tipped 15°, it would increase 
its power in the vertical meridiaji 1.25 D. ; and, if tipped 20°, 
it would increase its power in the vertical meridian 2.25 D. 
In each instance, however, it would also slightly increase the 
strength of the glass in the horizontal meridian. Now, if there 
was only a small amount of astigmatism against the rule, axis 
180°, this could be easily corrected by tilting the strong plus 
spherical glass. 

There is one disadvantage, incidental to the tipping of 

1 " On the Cylindrical Equivalent of Tilted Lenses, the Prismatic Equivalent 
of Decentered Lenses, and the Employment of such Lenses in Practice." 
Knapp's Archives of Ophthalmology ^ Vol. XX, pp. 1-25. 



322 THE REFRACTION OF THE EYE 

strong spherical glasses, which Holden points out. He says : 
" The spherical lens tilted on a horizontal axis has the disad- 
vantage that the refractive error is corrected only while the 
eye remains in a given horizontal plane. Suppose the upper 
edge of the glass tilted from the patient. Then, if he look 
through the lower part of the glass, the visual axis of the eye 
comes to form a smaller angle with the axis of the lens, and 
the effect of the tilting is correspondingly lost. If he look 
through the upper part of the glass, the visual axis is at a 
greater angle with the axis of the lens, and the refractive 
power is increased. For this reason, tilted spherical lenses are 
less adapted for distance than for reading." ^ 

Incidentally, it may be referred to again that myopic astig- 
matism with the rule^ when associated with myopia of high 
degree, can be corrected by tilting the strong spherical glass 
on its horizontal axis. This follows from the fact that in com- 
pound myopic astigmatism with the rule, just as hypermetropic 
astigmatism against the rule, the meridian of greatest error 
lies in the vertical plane, or one near it ; and, by tilting the 
strong sphere on its horizontal axis, it acts more strongly in 
the vertical plane than in the horizontal ; and, in this way, 
small amounts of astigmatism can be corrected when associated 
with high degrees of spherical error. Except in very high 
degrees of myopia, 10 to 18 D., with astigmatism of small 
amount, 1 to 3 D., with the rule, this method should not be 
adopted ; for, as pointed out by Donders : ^ " This means of 
correcting astigmatism is, however, capable of application only 
when relatively strong spherical glasses are required to neu- 
tralize the ametropia ; and then, too, a more perfect correction 
will be attainable by cylindrical curvature of one of the sur- 
faces. Only in aphakia can we advantageously, in my opinion, 
in order to correct a certain degree of astigmatism, make use 
of an oblique position of the glasses. Almost always it 

1 Loc. cit. 2 Accommodation and Befraction of the Eye^ p. 511. 



TORIC AND PERISCOPIC LENSES 323 

appears that when we give a certain inclination to the strongly 
•convex glass the acuteness of vision is improved, and the neces- 
sity of attending strictly to this in every case of aphakia is 
generally recognized." 

Before proceeding to give illustrative cases, I wish to speak 
very briefly of " toric " and " periscopic " lenses. 

Toric Lenses. — Dr. John Green gives the following defini- 
tion of a toric lens : " When a circle is revolved about a line 
in its own plane as an axis, a toric surface is generated. When 
the axis of revolution is a chord, other than a diameter of 
the generating circle, two toric surfaces are generated, by the 
greater and lesser arcs, respectively (Fig. 103, A). When the 





A B 

Fig. 103 (after John Green) . 

axis is taken outside the generating circle, the toric surface 
has the form of a ring (Fig. 103, B^. The plane of the cir- 
cumference described by the center of the generating circle 
cuts the toric surface equatorially. When the axis of revolu- 
tion is taken outside the generating circle, this plane cuts the 
toric surface in two equatorial circles, a lesser and a greater, 
which have a common center at the point in which the equa- 
torial plane cuts the axis of revolution, which point is the 
center of the torus. Every plane passing through the axis of 
revolution cuts the toric surface meridionally." ^ 

A toric lens, then, is one whose two cylindrical surfaces, 
with different length radii, are ground on one side of a lens 
with their axes at rigrJit anoies to each other. The other side 
oi the lens may be plane, or have a plus or minus sphere 

1 Transactions American Oph. Soc, Bd. Vol. V, 1888-90. pp. ()90-T17. 



324 THE REFRACTION OF THE EYE 

ground on it. Such glasses are especially applicable after 
cataract extraction, or in other cases when strong spheres 
have to be combined with cylinders. To give an example, 
say after cataract extraction a patient accepts + 10 D. -f 4 
D. cyl., 180°. Instead of giving this glass in the ordinary 
form, + 10 D. spherical ground on one side and + 4 D. cyl., 
180°, on the other, it can be ground in the toric form, as fol- 
lows : Grind + 5 D. sphere on one side, instead of the +10 D., 
and on the other side + 9 D. cyl., 180°, + 5 D. cyl., 90°. To 
give another example, say a patient accepts + 14 D. + 5 D. 
cyl., 180°. It may be written in a toric lens thus : + 8 D. 
+ 11 D. cyl., 180°, + 6 D. cyl., 90°. Such a combination 
makes a thinner glass, gives a wider field, causes less spherical 
aberration, and secures better vision, than the ordinary sphero- 
cylindrical glass. They are considerably more expensive than 
the ordinary glasses, but are much more preferable, and when 
the patient is able to pay for them should be prescribed. As a 
matter of fact, the profession has been tardy in recognizing 
the value of these glasses, for they are of signal advantage in 
many cases of refraction, even where no extraction has been 
performed, especially where the glasses are of a moderate or 
high power. Some examples will serve to illustrate their 
advantage. 

(1) Compound hypermetropic astigmatism, where the 
patient accepts + 2 D. + 2 D. cyl., 90°. A favorable toric form 
into which it can be transposed is, — 2 D. + 4 D. cyl., 180° -f- 
6 D. cyl., 90° ; in which case the —2D. spherical glass is 
ground on one side and the plus cylinders at right angles on 
the other. Or, secondly, one side of the glass could be left 
plane and plus cylinders ground at right angles on the other, 
thus + 2 D. cyl., 180° + 4 D. cyl., 90°. Thirdly, part of the 
sphere only could be ground on one side and cross cylinders 
on the other, thus + 1 D. + 1 D. cyl., 180° + 3 D. cyl., 90°. 
The first of the three toric forms into which the ordinary glass 



TORIC AND PERISCOPIC LENSES 325 

is converted is the best, as it gives a periscopic effect, of which 
we will speak presently under " periscopic " lenses. 

(2) Simple hypermetropia astigmatism ; patient accepts 
+ 4 D. cyl., 90°. A good toric form of this is - 2 D. + 2 D. 
cyl., 180° + 6 D. cyl., 90°. 

(3) Compound myopic astigmatism ; patient accepts — 2D. 
-2D. cyl., 180°. A good toric form is - 5 D. + 1 D. cyl., 
180° + 3 D. cyl., 90°. Again, take a higher myopia; say the 
patient accepts — 8 D. — 2 D. cyl., 180°. Part of the minus 
sphere can be ground on one side, and part on the other side in 
conjunction with the minus cylinder as a torus ; thus — 5 D. 
- 5 D. cyl., 180° -3D. cyl., 90°. 

(4) Simple myopic astigmatism; patient accepts — 4 D. cyl., 
180°. Toric as follows : -5 D. +5 D. cyl., 90° + l D. cyl., 180°. 

(5) Mixed astigmatism ; patient accepts — 2D. cyl., 180° 
+ 2 D. cyl., 90°. Toric as follows : - 4 D. + 6 D. cyl., 
90° + 2D. cyl., 180°. 

Where the glasses are not too strong, in transposing them 
into the toric form, we usually make them periscopic in shape 
also ; that is, we grind them in the form of a meniscus (see 
periscopic lenses immediately following). In this way the 
advantages of both forms (toric and periscopic) are gained. 
After cataract extraction and where astigmatism is present, 
the glasses are very heavy ; here part of the plus sphere must 
be ground on one side, while the remainder of the sphere, 
together with the cylinder, may be ground on the other side 
in the form of a torus. 

Dr. John Green, of St. Louis, and Dr. George C. Harlan, 
of Philadelphia, introduced toric lenses to the notice of the 
American profession, and made known by their writings ^ the 
advantages of such lenses over ordinary lenses. However, 
toric lenses have not met with the favor they so mucli deserve. 

1 Green, Transactions American Oph. Soc, Bd, Vol. Y., p. 709. Ilarlau, 
Log. cit., 1885, 1889. 



326 THE REFRACTION OF THE EYE 

Dr. George J. Bull,i of Paris, gives a full account of toric 
lenses in a late publication of his, and I refer my readers ta 
the writings of Harlan, Green, and Bull for a full exposition of 
the subject. 

Periscopic Lenses. — The term periscojnc comes from two 
Greek words, Tre/^t, around, about, and aKoirelv, to see ; that 
is, they are ground in such shape that the patient can see a& 
well through the margin of the glass as through the center. 
The form of such glasses, therefore, is that of a meniscus ; that 
is, concave on one side and convex on the other. If the con- 
cave side is more curved than the convex, it acts as a negative 
glass ; and if the convex side is more curved than the concave, 
it acts as a convex glass. 

Such glasses are not suitable after cataract extraction, or in 
high-power glasses of any kind, on account of their weight ; 
but weak and moderately strong glasses should always be 
ground in this form (meniscus) in preference to the ordinary 
form. In private practice I usually order this form of glass. 
The following are a few examples by way of illustration : — 

(1) Compound hypermetropic astigmatism ; patient accepts 
-f 2 D. -h 2 D. cyl., 90°. Periscopic form : -. 4 D. -1- 6 D. -}- 
2 D. cyl., 90°. 

(2) Simple hypermetropic astigmatism ; patient accepts 
-F 4 D. cyl., 90°. Periscopic form : - 4 D. + 4 D. -f- 4 D. 
cyL, 90°. 

(3) Compound myopic astigmatism ; patient accepts — 2 D. 
-2D. cyl., 180°. Periscopic form : -5 D. + 1 D. + 2 D. 
cyl., 90°. 

(4) Simple myopic astigmatism ; patient accepts — 4 D. 
cyl., 180°. Periscopic form : - 5 D. + 1 D. + 4 D. cyl., 90°. 

(5) Mixed astigmatism; patient accepts — 2D. cyl., 180° 
-h 2 D. cyl., 90°. Periscopic form : - 4 D. + 2 D. -|- 4 D.. 
cyl., 90°. 

1 Bull, Lunettes et Pince-Nez, Paris, G. Masson. 



ILLUSTRATIVE CASES 327 

t 
Even simple spherical glasses can be groiand in the peri- 
Boopic or meniscus form. For example, + 2 D. Periscopic 
form : — 2 D. + 4 D. Again, take a minus spherical glass, 
-2D. Periscopic form : - 4 D. + 2 D. 

Illustrative Cases 

In giving the following illustrative cases of astigmatism 
after cataract extraction, I have selected them from my private 
and hospital practice. I have also selected cases from the 
clinics of Professors Koosa, Webster, Emerson, Pomeroy, and 
Lewis, at the Manhattan Eye and Ear Hospital, who kindly 
allowed me to make use of any cases that I wished to. I may 
say here that these cases came under my personal observation 
while I was Interne at the Hospital. 

In selecting illustrative cases, I have had two points in 
view : first, to show typical forms of astigmatism after cataract 
extraction ; and, second, atypical and exceptional cases. In 
all of these cases, the ophthalmometer proved of the greatest 
possible value in recording the changes in the form of the 
cornea. 

Case CXIX. Astigmatism against the rule^ 3.50 D., axis^ 
180°, two weeks after operation; 1.50 i>., axis 180°, six weeks 
after extraction; Patient accepts + 10 i>. + .75 I), cyl.^ 180°,. 
and gets -||- vision^ six weeks after operation. — October 6, 1890; 
Sarah S., aged sixt3^-one years, in good health, had a simple 
extraction of cataract from the left eye by Dr. Webster. 
Smooth operation, the eye did well, and the patient was dis- 
charged after three weeks' stay in the hospital. 

Ophthalmometer. — Two weeks after operation, astigmatism 
against the rule, 3.50 D., axis 180°; three weeks, 3 D., 180° ; 
six weeks, 1.50 D., 180°. 

Test cards and trial le7ises. — Two weeks, 

L. V. = |-J W. + 8 D. 4- 2.75 D. cyl., 180°. 



328 THE REFRACTIOX OF THE EYE 

The ophthalmoscope and oblique illumination showed a 
light membrane in the pupil. This was needled. Four weeks 
later, and six weeks after the extraction, the ophthalmometer 
showed but 1.50 D. of astigmatism against the rule, axis 180°. 
Patient accepted + 10 D. + .75 D. cyl., 180°, and got V. = ff 
Read Jaeger No. 1 at 12 inches with + 13 D. + .75 D. cjd., 
180°. Both the distance and reading glasses were ordered. 

In testing for cataract glasses, part or the whole of the 
spherical error should be corrected before attempting to cor- 
rect the astigmatism, especially if the astigmatism be of small 
or only moderate degree. This conforms to the exception 
given in the first part of this book in fitting cases of astig- 
matism associated with high degrees of hypermetropia and 
myopia, except in cases where there has been a large amount 
of myopia before the operation. After cataract extraction the 
eye is rendered excessively hypermetropic, and, as a conse- 
quence, part of this spherical error has to be corrected before 
the effect of the cylindrical correction is appreciated. 

For reasons already given in the first part of the chapter, 
the patient will not usually accept as strong cylindrical glasses 
as indicated by the ophthalmometer, even though the astigma- 
tism be against the rule. The amount of the astigmatism 
after cataract extraction is not of as great importance as the 
axis ; for, as we can have no spasm of accommodation to deal 
with, by simply increasing the strength of the spherical glasses, 
we soon arrive at the glasses that give the best vision, pro- 
Added we have the correct axis at which to place the cylindrical 
glass. At least, this has been my experience. I have found 
the ophthalmometric the very best method of all the objective 
ones for keeping the record of the changes in the curvature of 
the cornea after cataract extraction. 

Case CXX. Astigmatism of large amount^ 8.50 Z)., against 
the rule, axis 15°, ttvo weeks after operation; 7 i>., axis 180°, 
seven iveeks after operation; |^ V. ivith + 10 D. + 5 i>. cyl., 



ILLUSTRATIVE CASES 329 

180°, seven weeks after the operation. — April 28, 1891, Israel K., 
aged forty-five years, in good health, had a simple extraction 
of cataract from the left eye by Dr. Roosa. The operation 
was without complication, the patient did well, and was dis- 
charged from the hospital at end of two weeks. 

Ophthalmoyneter. — Two weeks after operation, astigmatism 
against the rule, 8.50 D., axis 15° ; seven weeks, 7 D., axis 
180°. 

Test cards and trial lenses. — Two weeks, 

L- V. = ^^ W. + 10 D. + 6 D. cyl., 15°. 

The ophthalmoscope and oblique illumination showed a 
light membrane in the pupil. 

Seven weeks after the operation, the patient accepted 
+ 10 D. + 5 D. cyl., 180°, and got f^ V. ; and read Jaeger No. 
2 at 10 inches with + 4 D. sphere added. Both the distance 
and reading glasses were ordered. The astigmatism in this case 
did not decrease as much as is usual after extraction, being- 
reduced at the end of seven and one-half weeks only 1.50 D., 
that is, from 8.50 D. to 7 D. At the same time the axis 
changed from 15° to 180°, or the distance of 15°. 

Case CXXI. Astigmatism of large amount, 6 i)., against 
the rule^ two iveeks after operation; Reduced to 1.50 D., two 
months after operation ; Patient at that time accepted all of the 
astigmatism indicated hy the ophthalmometer and got -||- vision. — 
November 4, 1896, Mrs. S. J. C, aged fifty-five years, in good 
health, had a simple extraction of cataract from the left 
eye by me at her home. The operation was Avithout com- 
plication, and the patient was discharged on the sixteenth day. 

Ophthalmometer. — Sixteenth day, astigmatism against the 
rule, 6 D., axis 150° ; one month, 4 D., axis 150° : two and 
one-half months, 1.50 D., axis 15°. 

Test cards and trial lenses. — Sixteenth day, 

L. V. = |-J W. + 10 D. -f- 4 D. cyl., 150^ 



330 THE REFRACTION OF THE EYE 

Ophthalmoscope and oblique illumination show a clear 
pupil. 

Two and one-half months after the operation, the ophthal- 
mometer showed astigmatism of only 1.50 D., which the 
patient accepted in full. 

L. V. = ffW. -f-13D. + 1.50D. cyl., 150°. 

Reads Jaeger No. 1 at 12 inches with + 17 D. + 1 D. cyl., 
150°. Both the distance- and reading glasses were ordered, 
which she has worn with comfort ever since, two and one-half 
years, and maintains the same good vision. 

It will be noticed in this case that the cylinder had to be 
reduced in strength in the reading glass. The reason for this 
has already been discussed in this chapter. 

Case CXXII. Astigmatism with the rule^ 1.50 i)., twelve 
days after operatio7i; Astigmatism did not change in amount or 
axis ; Patient accepted the full amount of astigmatism indicated 
hy the instrument^ and obtained |-g V, when combined with the 
proper spherical glass. — October 22, 1890, Julia A. W., aged 
sixty-five years, in fairly good health, had a simple extraction 
of cataract from the left eye by Dr. Pomeroy. The operation 
was without complication, and the patient was discharged on 
the twelfth day. 

Ophthalmometer. — Twelve days, astigmatism with the rule, 
1.50 D., axis 90°; one month, the instrument gave exactly the 
same reading again. 

Test cards and trial lenses. — Twelve days, 

L. V. = 1^ W. 4- 11 D. + 1.50 D. cyl., 90°. 

One month, the ophthalmometer gives the same reading as 
at first. 

L. V. = 1^ W. 4- 11 D. + 1.50 D. cyl., 90°. 

Reads Jaeger No. 1 at 10 inches with + 5 D. added. 



ILLUSTRATIVE CASES 331 

The ophthalmoscope and oblique illumination show a clear 
pupil. Both the distance and reading glasses were ordered. 

Tilting the glasses in this case improved the vision very 
little, if any, since the astigmatism was in the horizontal merid- 
ian and the cylinder was worn with its axis at 90°. I have 
found the same thing true many times when the axis of the 
cylinder was several degrees distant from the horizontal merid- 
ian, for example, the case immediately preceding this one. 

Case CXXIII. Astigmatism against the rule, 3 i>., three 
weeks after operation ; 1 _Z)., six weeks after operation ; No cylin- 
der accepted on the final test. — September 21, 1891, George H., 
aged fifty years, in good health, had a simple extraction of 
cataract from the right eye by Dr. Emerson. The operation 
was without complication, and the patient was discharged at 
the end of three weeks. 

Ophthalmometer. — Three weeks, astigmatism against the 
rule, 3 D., axis 180° ; four weeks, 2.50 D., axis 180° ; six 
weeks, 1 D., axis 180°. 

Test cards a7id trial lenses. — Three weeks, 

R. V. = f ^ W. + 10 D. + 2.50 D. cyl., 180°. 

Ophthalmoscope and oblique illumination show a clear 
pupil. 

Six weeks, astigmatism equals ID., axis 180°. 

R. V. =f^W. +11D. 

Reads Jaeger No. 1 at 12 inches with + 15 D. No cylin- 
drical glass was accepted on this final test. Ordered botli the 
distance and reading glasses. 

A slight tilting forward of the upper edge of the spherical 
glass in this case made the vision better than with the com- 
bination of any cylinder. Moreover, as the astigmatism was 
exactly in the vertical meridian, and against the rule, a simple 
tilting of the sphere on the horizontal axis was easil}^ made. 



332 THE REFRACTIOX OF THE EYE 

Case CXXIV. Astigmatism of very large amount^ 16 i>.,. 
against the rwie, tivo and one-half tueeks after operation; 4 D., 
three months after operation; Patient accepts 3.50 D. cylinder 
ivith proper sphere and gets |-§- F"., after three months. — May 28, 
1891, Bridget M., aged fifty-five years, in good health, had a 
simple extraction of cataract from the right eye by Dr. Emer- 
son. The operation was without complication, and the patient 
was discharged two and one-half weeks after the operation. 

Ophthalmometer. — Two and one-half weeks, astigmatism 
against the rule, 16 D., axis 180°; three months, 4 D., axis 180°. 

Test cards and trial lenses. — Two and one-half weeks, 

R. V. = 2V0 ^^- + 6 D. + 12 D. cyl., 180°. 

The ophthalmoscope and oblique illumination showed a 
clear pupil. 

Three months, 

R. Y. = 11 \y. + 12 D. -I- 3.50 D. cyl., 180°. 

Reads Jaeger No. 1 at 12 inches with + 4 D. added. 
Both the distance and reading glasses were ordered. 

The very large amount of astigmatism, 16 D., in this case, 
was reduced to 4 D. in the course of three months' time. It 
was on account of this very large amount of astigmatism that 
we waited longer than usual before giving the final test, in 
order that it might be reduced to its lowest amount. 

On the first test the patient accepted -f 12 D. cylindrical 
glass and only H- 6 D. spherical glass ; while at the final test 
the patient accepted -f 12 D. spherical glass, and only + 3.50 
D. cylindrical glass. 

This illustrates a common occurrence after cataract extrac- 
tion ; to wit, that as the cylinder diminishes in strength, the 
sr)here, as a rule, increases in strength, and vice versa. 

It may be asked how it was possible to measure so much 
astigmatism (16 D.) with the Javal ophthalmometer, when the 



ILLUSTRATIVE CASES 33B 

graduated mire has only eight steps on it, representing but 
8 D. In such a case as this, it is necessary to note the posi- 
tion of the mires on the arc, which has diopter marks on its 
posterior edge, in the primary position ; and then again in the 
secondary position after the images have been made to touch 
again. The difference between the two numbers will give the 
number of diopters of astigmatism. 

Say the movable mire (in the instrument with the single 
movable mire, the old one) stands at 26 in the horizontal merid- 
ian when the images of the mires touch ; 26 added to 20 (20 
being the distance in diopters the fixed mire stands on the oppo- 
site side of the arc) equals 46 D., the refractive power of the 
cornea in the horizontal meridian. Then when the arc is turned 
to 90°, say the images separate, showing astigmatism against the 
rule, and that the movable mire has to be moved along the arc 
till it stands at 10 before the images touch again. This added 
to 20, the distance of the fixed mire, would give 30 D., the 
refractive power of the cornea in the vertical meridian. Now 
the difference between 46 and 30 D. = 16 D., the difference in 
refractive power of the two principal meridians, or the amount 
of the astigmatism. 

Case CXXV. — Astigmatism of large amount^ 15 i>., against 
the rule, three weeks after the operation; Reduced to 13 D. after 
two months, and only to 12 I), after one year and a half leaving 
12 D. astigmatism permanently ; Patient accepted + 11.50 B. 
cylinder combined with 4 D. sphere ; Axis of the astigmatism did 
not change in the first two months, hut had made a change of 15° 
when seen in eighteen months. — March 16, 1891, Julia G., aged 
seventy-seven, in good health, had a simple extraction of 
cataract from the left eye by Dr. G. M. Black.^ The opera- 
tion was without mishap, but during the course of healing the 
wound pulled open twice, and when finally healed there Avas a 

1 Ex-House Surgeon, Manhattan Eye and Ear Hospital. 



334 THE REFRACTIOX OF THE EYE 

deeply grooved scar at the site of incision. Pupil circular and 
central, but at time the patient was discharged, twenty-first 
day, there was a membrane in it. One month after the opera- 
tion a needling was performed by Dr. Black, which was not 
successful, and three days later a second needling was done, 
this time leaving a clear pupil. 

Ophthalviometer. — Three weeks, astigmatism against the 
rule, 15 D., axis 165°; two months, 13 D., axis 165°; eighteen 
months, 12 D., axis 180°. 

The ophthalmoscope showed an opening in the membrane in 
the pupil 3 mm. long by 2 mm. broad ; pupil central and 
■circular. 

Test cards and trial lenses. — 

. One month, L. V. = ^Vo W. + 3 D. + 12 D. cyl., 165°. 
Two months, L. V. = ^ W. + 4 D. -f- 11.50 D. cyl., 165°. 

On account of the very large amount of astigmatism pres- 
ent, due to the grooved wound, distance glasses only were 
ordered, -f 4 D. +11.50 D. cyl., 165°, and she was told to 
come for another test in four months. She returned after 
sixteen months, saying the glasses had been satisfactory until 
the last three months. 

The ophthalmometer showed the astigmatism at this time, 
eighteen months after the extraction, to be 12 D., axis 180°, in- 
stead of 165°, as at first. There is still a decided groove at the 
upper margin of the cornea. 

Test cards and trial lenses. — 

L. y. = 1^ W. + 6.50 D. + 10.50 D. cyl., 180°. 

Reads Jaeger No. 1 at 9 inches, with + 11 D. +10. D. 
cyl., 180°. Both the distance and reading glasses were ordered. 

It will be seen that the vision with this last glass was in- 
creased to -|^, while 1^ was the best vision to be obtained 
two months after the operation. Furthermore, the axis of the 
glass had to be changed 15°. 



ILLUSTRATIVE CASES 335 

This change in the axis of the astigmatism did not take 
place until after two months following the operation. This I 
have seen in but one other case so long after the extraction. 
It will be noticed, too, that the strength of the spherical glass 
had to be increased as the strength of the cylinder was dimin- 
ished, a point already noted above in other cases. 

An 11.50 D. cylinder is the strongest cylindrical glass that I 
have ever seen worn ; but in this case it gave the best vision, 
and I did not hesitate to order it. Even eighteen months after 
the operation, + 10.50 D. cylinder for distance, and + 10 D. 
cylinder for reading, in combination with spheres, had to be 
ordered. 

Dr. Pfingst, already quoted, said that in his series of fifty 
cases none accepted more than a 6 D. cylinder, although in 
some of his cases the instrument showed as much as 22 D. of 
astigmatism shortly after extraction. This case, it will be seen, 
accepted a much stronger cylinder, and, moreover, Avore it with 
comfort. It is an exceedingly rare case, however. But the 
next following case to be reported is even more remarkable as 
to the strength of cylinder accepted, 16 D. cyl., 15°, twenty-six 
days after the extraction. This glass was not given perma- 
nently. The large amount of astigmatism was due to folding 
of the iris along the whole length of the wound. 

Case CXXVI. Astigmatism of excessive amount^ 20 D., 
against the rule, from incarceration of the iris in the around 
during healing; Patient accepted 16 D. cgL, without a)iy 
sphere, tweyity-six days after extraction. — January 17, 1891, 
R. S. D., aged seventy-tliree years, general health good, had 
a simple extraction of cataract from the right eye b}' Dr. Roosa. 
Two or three drops of vitreous w^ere lost at time of the opera- 
tion. During the healing process the upper half of the iris 
folded backward, the pupillary edge coming in contact with the 
ciliary body, Avhile the upper or fokled portion of the iris 
became incarcerated in the whole length of the wound, prevent- 



336 THE EEFRACTION OF THE EYE 

ing the wound from healing smoothly. The patient was dis- 
charged after twenty-six days. 

Ophthalmometer. — Twenty-sixth day, astigmatism against 
the rule, 20 D., axis 15°. 

Test cards and trial lenses. — 

R. V. = 2V0 ^^- + ^^ ^' cyi-' 15°. 

Ophthalmoscope and oblique illumination show a membrane 
in the pupil. The pupil is drawn upward so far that it looks 
as if an iridectomy had been done above. 

This patient was instructed to return in a month to have a 
needling performed, but he did not come again, and he has 
been lost sight of. In regard to the excessive amount of 
astigmatism in this case, and the very strong cylinder accepted, 
it is fair to presume that the astigmatism did not diminish a 
great deal after the patient went from under observation; 
because the measurements were made on the twenty-sixth day 
after extraction, about one month, after which length of time 
the astigmatism, as a rule, changes but little, and after six 
weeks' time practically none. 

A 16 D. cylinder is by far the strongest cylinder I have 
ever seen accepted. But this glass in the present case gave 
the best vision to be obtained. I would call to mind again, 
however, the case of Dodd (eye not aphakial), v/here he gave 
28 D. as a cross-cylinder, as follows : — 

- 12 D. cyl., 95° -f 16 D. cyl., 5°.i 

1 The patient who accepted this phenomenal glass had had trachoma, and V.. 
without correction was only -^. The ophthalmometer showed astigmatism 
against the rule, 28 D., axis 5° + or 95° — . The refractive power of the cornea 
in the meridian at 5° was 60 D., and in the meridian at 95°, 32 D. ; an excess in 
power of 17 D. in the meridian at 5°, and a deficiency of 11 D. in the meridian 
at 95°, from the average refractive power of the cornea, which is about 43 D. 
The patient had in addition to the mixed astigmatism (which was corneal) 5 D. 
of hypermetropia. This corneal correction (— 17 D. cyl., 95° + 11 D. cyl., 
5°), added to an hypermetropia of 5 D. (- 12 D. cyl., 95° + 16 D. cyl., 5°),. 



ILLUSTRATIVE CASES 337 

Case CXXVII. Astigmatism of very large amount^ 22 D. 
against the rule^ two weeks after operation; 5 D. against the rule 
five months after ojjeration^ at ivhich point it remained stationary ; 
Change in axis of 10° during healing. — February 19, 1898, 
Ann F., aged fifty-five, in good health, had a simple extraction 
of cataract from the left eye by me at the Manhattan Eye and 
Ear Hospital. The eye healed quickly, but on the seventh day 
the patient fell over backwards from a stool on which she was 
sitting and pulled the wound open. This healed again, but left 
a deeply grooved wound. The patient was discharged on the 
seventeenth day ; pupil central and circular. 

Ophthalmometer. — Seventeenth day, astigmatism against 
the rule, 22 D., axis 180°; one month, 12 D., axis 170°; five 
months, 5 D., axis 170° ; one year, 5 D., axis 170°. 

Test cards and trial lenses. — 

Seventeen days, L. y. = -52_o_. ^y. 4_ 8 D. + 8 D. cyl., 180°. 

One month, L. V. = |f W. + 10 D. + 8 D. cyL, 170°. 

Five months, L. V. = -|^ W. + 12 D. + 3.50 D. cyL, 170°. 

Jaeger No. 1 at 12 in., with + 16 D. + 3 D. cyl., 170°. 
Ordered both the distance and reading glasses. This patient 
was seen one year after the extraction, and the astigmatism 
had not changed after the first five months. Twenty-two 
diopters is the highest amount of astigmatism after a cataract 
extraction I have ever seen. Although the ophthalmometer 
registered this very great amount of astigmatism, at no time 
would the patient accept more than an 8 D. cyl. 

gave the immense improvement in vision =-^, or 15-fold Letter tlian the vision 
without the glass. 

With his glasses the patient could read newspaper print and follow his trade, 
that of a shoemaker. The doctor remarked on the case that without the ophthal- 
mometer he could not have fitted it correctly, because subjective tests alone, 
or even with the aid of the ophthalmoscope and retinoscopo, would have been 
almost useless, in which I agree with him. 

For a full report of the case, see Ophthalmic Bccord, Vol. V, p. 220. 



338 THE REFRACTION OF THE EYE 

Case CXXVIII. Astigmatism against the rule, 3D., twa 
and one-half weeks after operation; Astigmatism with the rule, 
2 D., three months after operation, which remained as such for 
about four years, ivhen the patient ivas last seen; Ophthalmometer 
showed no cor7ieal astigmatism whatever before the extraction. — 
January 29, 1891, H. R. N., aged seventy-one years, in good 
health, had extraction of cataract, with iridectomy, from the 
left eye by Dr. Lewis. A mild iritis followed the extraction, 
but the patient made a good recovery, and was discharged on 
the eighteenth day. 

Ophthalmometer. — Two and one-half weeks, astigmatism 
against the rule, 3 D., axis 180° ; three months, astigmatism with 
the rule, 2D., axis 90°; and three and one-half years later the 
astigmatism was the same exactly as to amount and axis. 

Test cards and trial lenses. — Two and one-half weeks, 

L. V. = f^ W. + 10 D. + 1 D. cyl., 180°. 

Ophthalmoscope and oblique illumination showed a light 
membrane in the pupil. This was needled three months later. 
At time of needling the ophthalmometer showed that the astig- 
matism had changed from 3 D. against the rule to 2 D. with 
the rule, axis 90°. August 7, 1894, over three and one-half 
years later, the corneal astigmatism still remained 2D., with the 

rule, and 

L. V. = II W. -f 9 D. -f- 1 D. cyl., 90°. 

Jaeger No. 1 at 12 inches, with -f 16 D. spherical glass. 

Case CXXIX. Astigmatism against the rule, 10 D., four 
weeks after operation; Six months after operation, astigmatism 
u'ith the rule, 4.50 D., which four Quonths later (^and ten months 
after operation) had diminished to about 1 D. with the rule. — 
April 6, 1891, Phoebe W., aged fifty-five years, in good health, 
after a preliminary iridectomy, had extraction of cataract 
from the right eye by Dr. Roosa. Iritis followed, moderately 



ILLUSTRATIVE CASES 339 

severe. The patient was discharged on the twenty-eighth 
day. 

Ophthalmometer. — Four weeks, astigmatism against the 
rule^ 10 D., axis 180°; six months, astigmatism with the ruley 
4.50 D., axis 75°. 

Test cards and trial lenses. — Four weeks, 

R. V. = ^-^% W. + 13 D. + 8 D. cyl., 180°. 

Ophthalmoscope and oblique illumination show a membrane 
in the pupil. Patient advised to have a needling performed, 
but she wished to wait some months. Six months later 
needling was performed, and one week after the needling, 

R. V. = 1^ W. + 12 D. + 2.50 D. cyh, 75°. 

Reads Jaeger No. 1 at 10 inches, with 3.50 D. sphere 
added. Four months later this patient was examined by 
Dr. Lewis, and he found the astigmatism to be about 1 D. 
with the rule, axis 60°; the vision had increased to |-§- W. + 
10 D. sphere, the patient not accepting any cylinder. 

This patient had had a cataract removed from the left e3"e, 
previously to the operation on the right eye, with a good result. 
The case is reported to show the remarkable change in the 
astigmatism that occurred in less than a year's time. 

Case CXXX. Astigmatism with the rule^ 4.50 D., three 
and one-half weeks after operatio7i ; Changed to 1.50 D. against 
the rule^ after three years^ and remained thus at the end of five 
years from operation; Case remarkable also for aciiteness of 
vision obtained, ^^, and for accommodative po2cer after the e.r- 
traction of the lens. — January 27, 1894, Emil C, aged forty- 
two years, in good health, had extraction of a '^ black" cataract, 
with iridectomy, from the right eye by me at his home. The 
wound did not heal completely for a week, and only a very 
shallow anterior chamber formed, but at the end of the week 
the wound closed completely, and the eye recovered with the 



340 THE REFRACTIOX OF THE EYE 

remarkable vision of -|-§- (Snellen). At the end of three months 
it was discovered that he had the power of accommodation in 
the e3'e ; and for that reason the case was reported at length in 
the 3Ianliattan Eye and Ear Hospital Reports^ January, 1895. 
His vision at time of the operation was : — 

T? Y _ 20 T Y _ 2_0 

Jaeger No. 12 at 10 inches right eye, and No. 9 at 10 
inches left eye. Though his vision was so good by the Snellen 
test, he could not recognize friends or members of his own 
family on the street, had not worked for five years, and insisted 
on the operation being done. 

Ophthalmometer. — Before the operation, astigmatism with 
the rule, .50 D., axis 90° + or 180° — in each eye ; three and 
one-half weeks after the operation, astigmatism with the rule, 
4.50 D., axis 90° ; three months after the operation no astig- 
matism whatever ; three years, astigmatism against the rule, 
1.50 D., axis 5°, and five years after, exactly the same as at 
three years, both as to the amount and axis of the astigmatism. 

Test cards and trial lenses. — Three and one-half weeks, 

R. V. = 1^ W. 4- 9 D. 4- 3.50 D. cyl., 90°. 

Three months, R. V. = f^ W. -f 11.50 D. 

Jaeger No. 1 at 12 to 15 inches, with -f- 15.50 D. 

The patient discarded the reading glasses after wearing 
them a few weeks, and wore the distance glasses for all pur- 
poses. With this distance glass (11.50 D.) he read |-J =- 
(Snellen), and Jaeger No. 1 from 8 to 221 inches, without 
changing the position of the glass at all on his nose. 

May 6, 1897, three years and four months after the opera- 
tion, I made the following note in my case book : — 

"Ophthalmometer, astigmatism against the rule, 1.50 D., 
axis 5°. 

" R. Y. +\^- W. + 10.50. D. +1.50 D. cyl., 5°. 



ILLUSTRATIVE CASES 341 

"Jaeger No. 1, with the same glass, from 8|- to 22^ inches." 
When last examined, five years after the operation, the 
astigmatism was the same as at the end of three years, and the 
patient had vision ^^ — and still the power of accommodation. 
The ophthalmoscope and oblique illumination showed the 
fundus of the eye normal and the media perfectly clear. The 
pupil was oval (from iridectomy above) and free from mem- 
brane, except a very narrow strip at the margin. 

Case CXXXI. Astig7natism with the rule, 3D., three weeks 
-after operation; 1.50 D., against the rule, three months after ; 
Accepts + 1 D., cylindrical glass, with sphere for distance, hut no 
cylinder for reading. — November 26, 1890, M. R., aged forty- 
five years, in good health, had a simple extraction of cataract 
from the left eye by Dr. Webster. A mild iritis occurred 
during healing, but the patient made a good recovery and was 
discharged on the twenty-third day. 

Ophthalmometer. — Three weeks, astigmatism with the rule, 
3D., axis 90°; three months, astigmatism against the rule, 
1.50 D., 180°. 

Test cards and trial lewises. — 

Three weeks, L. V. = f§ W. + 8.50 D. -i- 2.75 D. cyl., 90°. 
Three months, L. V. = f§ W. + 10.50 D. + 1 D. cyl., 180°. 

Patient was given + 14 D. for near work, and + 10.50 D. + 
1 D. cyl., 180° for the distance. 

The ophthalmoscope and oblique illumination showed a clear 
pupil and media. 

Case CXXXII. Astigmatism against the m(h\ iritJi a eJunige 
in the axis of 30° within one week's time, due pei-Jiaps to a stretch- 
ing of the wound from needling, which iras pe)for))ied o)ie ))io)ith 
<xfter the extraction. — March 18, 1891, J. S., aged iifiy-six 
years, good health, had a simple extraction of cataract from the 
left eye by Dr. Pomeroy. The iris was wounded at time of 



342 THE REFRACTIOX OF THE EYE 

the operation and iritis followed. The patient was discharged 
in one month. 

OphtJialmometer. — One month, astigmatism against the 
rule, 4 D., axis 180°. Five weeks, and after needling one 
week previously, astigmatism against the rule, 3 D., axis 30°. 

Test cards and trial lenses. — 

L. V. = f ^ W. + 10 D. + 3 D. cyl., 180°. 

Ophthalmoscope and oblique illumination show a membrane 
in the pupil ; needling performed. One week later, 

L. V. = f^ W. + 9.50 D. + 2.25 D. cyh, 30°. 

This patient unfortunately was not seen again at the clinic. 
The interesting point in the case is the marked change in the 
axis of the astigmatism after the needling, as much as 30°. 
This was due, I think, to stretching of one end of the wound, 
though it may have been from the uneven healing of the 
wound. 

Case CXXXIII. Astigmatism 6 D., axis 45°; Section was 
made directly above for the extraction^ hut the nasal side of the 
ivound {left eye') broke open during a needling on the twelfth day ; 
Ultimate vision JJ. — October 8, 1890, E. B., aged fifty-three 
years, good health, had a simple extraction of cataract from the 
left eye by Dr. Webster. Xo accident during the operation, 
and the eye did well. Twelve days later, when Dr. Webster 
attempted to perform a needling, the patient squeezed the 
eye violently and opened the wound at the nasal extremity. 
Within four days the wound had healed again, but no further 
attempt to needle was tried until five months later, when a 
successful needling was performed. 

Oj^htlialmometer. — Seventeenth day, astigmatism with the 
rule, 6 D., axis 45° ; five months, 1.50 D., axis 45°. 

Test cards and trial lenses. — Seventeenth day, 

L. V. = -jVo W. + 9 D. + 6 D. cyl., 45°. 



ILLUSTRATIVE CASES 343 

The ophtlialmoscope and oblique illumination show a mem- 
brane in the pupil. 

Five months, and after needling, 

L. y. = 11^ W. + 13 D. + .50 D. cyl., 45°. 

Reads Jaeger No. 1 at 10 inches, with + 18 D. sphere, with- 
out any cylinder. Both the reading and distance glasses Avere 
ordered. 

As a rule, after cataract extraction, the axis of the correct- 
ing cylinder is worn horizontally with the direction of the 
wound; but exceptionally it has to be worn with its axis at 
right angles to the direction of the wound, as in the few cases 
where the astigmatism is with the rule after the operation for 
cataract. The usual position for the corneal section being 
directly above in cases of cataract extraction, the astigmatism 
that follows, in the great majority of cases, is against the rule, 
and requires the cylinder to be worn with its axis at or near 
180°, or horizontally with the direction of the corneal section. 
The exceptions to this general rule are: First, where there has 
been a high degree of myopia, and the astigmatism is against 
the rule, a minus cylinder must be worn to correct the astigma- 
tism, when the axis of the cylinder must be worn at or near 
90°, or at right angles to the corneal section ; second, where the 
astigmatism is with the rule after extraction, when the cyl- 
inders must be worn at or near 90°, or at right angles to the 
corneal section. 

In the case last reported the section was directty above, but 
during an attempted needling the patient squeezed the eye 
violently and pulled the Avound open at its nasal end (at a 
meridian near 135°), and the grooved wound that followed at 
this position caused the axis, or the meridians of greatest and 
weakest curvature, to be at 45° and 135° respectively. The 
ophthalmometer showed this to be so. 

In makinq; the section for cataract extraction, tlierefore^ 



844 THE REFRACTION OF THE EYE 

unless some special reason comes to bear on tlie case, it should 
always be made directly above. The astigmatism that follows 
is usually in or near the vertical and horizontal meridians, and 
in nearly every case against the rule. We have already pointed 
out the advantage of tilting the strong plus spheres if the 
astigmatism is against the rule and affects the vertical merid- 
ian. If the astigmatism does not lie in the vertical meridian, 
or one near it, this tilting of the strong spheres is not of much 
advantage ; hence, since we can in a measure determine the axis 
of the astigmatism after extraction by the location of our 
section, we should place it, as is usually done, directly above 
— the most favorable position. 

Of course, the section for cataract extraction could be 
placed below, but the surgical and optical reasons against this 
are quite apparent. Even in making section for iridectomy 
in glaucoma we should, where it is possible, always make the 
section above. First, for the reasons given above as to the 
favorable form of astigmatism it causes ; second, and most im- 
portant, by the iridectomy being made above the coloboma in 
the iris is hidden almost completely by the upper lid,- thereby 
causing less deformity and giving better vision by cutting off 
the excess of light and preventing diffusion circles, which 
would follow if the artificial pupil was made below where it 
could not be covered. 

Some regard must be had, therefore, to the position of the 
section in cataract extraction, if we wish to do the best by 
our patients. Astigmatism with oblique axes, that is, with the 
chief meridians off from 90° and 180°, other things being equal, 
is always worse than the astigmatism where the vertical and 
horizontal meridians are at fault. Consequently, where we 
have a controlling influence on the axis of the astigmatism, we 
should exert it to the best advantage, and place it as near as 
possible in the vertical and horizontal meridians of the cornea. 

There is one other class of cases of which I wish to speak 



ILLUSTRATIVE CASES 



345 



briefly before closing this chapter — I mean cases of myopia 
with cataract. 

Dr. PercivaP says some operators have expressed great 
surprise at the marked change in the refraction in such cases 
after cataract extraction, when, as a matter of fact, they should 
expect it. For instance, after the statistics given by Helm- 
holtz, Bonders, and others, he shows by calculation that an 
axial myopia of between 25 D. and 26 D. is entirely corrected 
by simply extracting the lens from such an eye. 

Since it requires about + 11 D. to correct the emmetropic 
eye after cataract extraction, it would naturally be supposed 
that a myopia of 26 D., after cataract extraction, would require 
a lens representing the difference between — 26 D. and + 11 D. 
(— 15 D.) to correct it for the distance. But such is not the 
case, and Dr. Percival, after giving a table of such cases, 
remarks : — ■ 

" It will be noticed that the change in refraction due to the 
operation increases with the previous degree of axial myopia.^^ 

In other words, the higher the degree of myopia before the 
operation, the greater the influence proportionally will the ex- 
traction of the cataract have on the correction of same. I repro- 
duce, in part, his table. The length of the emmetropic eye in 

this table is 22.8 mm. 

Table 





Anteeo-Postkeior 

Dimension, 

OE Optic Axis 


PowEE OF Glass 

TO COEEECT 
BEFOEE OpEEATION 


Powee OF Glass 

TO COEKECT 

AFTER Extraction 


Change in 
Eefkaction 


23 mm. 


- .50 D. 


+ 11.2 D. 


11.7 D. 


26 mm. 


- 9.9 D. 


+ 7. D. 


10.9 D. 


29 mm. 


- 19.2 D. 


+ 2.9 D. 


22.1 V>. 


32 mm. 


- 28.50 D. 


- 1.25 P. 


27.3 V). 





Knapp's Archives of Ophthalmology, Bd. Vol. XXVI, pp. 1-4. 



346 THE REFPtACTIOX OF THE EYE 

I give this table in order that those who are not acquainted 
with the facts in such cases, as regards the change of refraction 
by extraction of the lens from myopic eyes, may not make 
errors in correcting them ; and so that they will not be at a 
loss to account for so marked a change in the refraction. 
Moreover, it may prove of value, and serve as a warning also, 
perhaps, to those who intend to, or do now, remove the trans- 
parent crystalline lens in high degrees of myopia. 

I have never removed the transparent lens in the living sub- 
ject, but those who advocate it claim that it can be safely done 
on suitable eyes ; and that the eye, by the operative procedure, 
remains only slightly myopic, or may be rendered hyperme- 
tropic. They also claim that visual acuity is increased by the 
retinal images becoming larger, that the strain of convergence 
is lessened, and that congestion of the fundus is relieved. 
Certainly, some very favorable reports of cases of high degree 
of myopia treated by removal of the crystalline lens have been 
made in the last few years. However, while keeping in mind 
the advantages of this method of treatment of high myopia, 
we should not forget the contraindications and dangers of the 
operation. 

Contraindications. — (1) Any degenerative changes in the 
choroid or retina, especially if these changes are near the 
macula ; (2) Vitreous opacities, which usually indicate de- 
generative changes in the blood vessels ; (3) Marked corneal 
opacities ; (4) Myopia of less than 12 D. ; (5) Any condition 
that contraindicates extraction of senile cataract, as trachoma, 
detachment of the retina, advanced age, etc. 

The chief dangers of the operation itself are : (1) Intra- 
ocular hemorrhage ; (2) Detachment of the retina. 

When we consider that one of the contraindications to the 
operation is a myopia of less than 12 D., and another, and the 
most serious one, degenerative changes in the choroid and 
retina, and remember how few eyes there arp with myopia of 



HIGH MYOPIA WITH CATARACT 347 

more than 12 D., with sound fundi, it will be apparent how few 
really suitable eyes there are for the operation. Furthermore, 
to obtain that ideal condition, about 2 D. of myopia remaining 
after the operation, so that the patient would not need a glass 
for the near point, the eye must have had at least 30 D. of 
myopia before the operation. Now 30 D. of myopia is so rare 
as hardly ever to be met with, and Avhen it is encountered, 
degenerative changes in the fundus are almost certain to be 
present in such a highly myopic eye, which contraindicate 
operative procedure. Hence the ideal sought for in these cases 
is clearly out of the question, theoretically at least, as shown 
by the table of Percival. Even to obtain emmetropia after the 
operation, theoretically, a myopia of 25 or 26 D. is necessary 
before the operation. Practically, as shown by Von Hippel 
and others, emmetropia may be obtained by extracting the lens 
(discission of course) in myopia of only 15 D. ; and in myopia 
of 18 to 20 D., it is obtained in about 25 per cent of the cases. 
The operative treatment of high degrees of myopia by the 
removal of the crystalline lens is still on trial, and time and 
experience must decide for or against it. 






f 



CHAPTER XI 

EXCEPTIONAL CASES 

By exceptional cases, I mean cases in which the result of 
subjective examinations of the visual power differs widely 
from the reading of the ophthalmometer, either as to the axis 
or amount of the astigmatism, or as to both, as found by sub- 
jective examination with the test cards and trial lenses. All 
cases wherein the reading of the instrument differs as much as 
15°, as regards the axis, and as much as ID. as regards the 
amount (except after cataract extraction) of the astigmatism, 
as found by subjective and by other objective tests, I regard 
as exceptional. Such cases, in my experience, are relatively 
rare, and hence I regard them as exceptional. 

Javal, as far back as 1882, in the examination of over one 
hundred eyes, found the total and the corneal astigmatism was 
the same except in four cases. But further and more extensive 
examinations since then have established the fact that the 
corneal astigmatism as measured by the ophthalmometer, and 
the total astigmatism, differ in amount to the extent of about 
.50 to .75 D. in the great majority of cases. When the corneal 
astigmatism is " with the rule," the total astigmatism is found 
to be less than the corneal by .50 to .75 D., and when the corneal 
astigmatism is "against the rule," the total astigmatism ia 
found to be more than the corneal by .50 to .75 D. The axis of 
the total astigmatism usually coincides with that of the corneal, 
or to within 10°. Keeping these points in mind, and taking into 
account the amount of difference to be expected between the 
corneal and the total astigmatism, the subjective examination is- 
made easy and satisfactory. In fact, as a general practice, in 

348 



EXCEPTIONAL CASES 349 

patients forty years of age and over, a single test with the 
ophthalmometer and a subsequent test with test cards and trial 
lenses is quite sufficient examination in order to arrive at the 
right glasses to be given, and, of course, without a mydriatic. 

In patients under forty years of age, two tests, as a rule, are 
enough, and seldom is it necessary to give three, even in cases 
of children, and then without a mydriatic, except in rare in- 
stances where spasm of accommodation is present (strabismus 
cases are, of course, here excluded). It has been my experience, 
taking cases as they come, that I get better results without 
a mydriatic than with it (with the exception above noted). 
The mydriatic, besides upsetting the natural relation between 
the accommodation and the convergence, often causes us to 
give the patient. too strong a glass, and one which he will often 
not wear after coming from under the influence of the mydriatic. 
Therefore, except in cases of excessive and irregular action 
of the ciliary muscle (spasm of accommodation), I believe the 
practice of using mydriatics a bad one, and one to be avoided. 
My experience in thousands of cases has taught me this. 

But even with careful testing by an experienced hand, both 
without and with a mydriatic, there are a few cases where the 
astigmatism indicated by the ophthalmometer differs widely 
from that found by further objective and subjective examina- 
tion. Where such discrepancies occur, they are to be ac- 
counted for by one or more of the following causes : — 

1. Error in observation. 

2. Abnormal lenticular astigmatism, from whatever cause. 

3. Position of the glasses in front of the eyes. 

4. Angle alpha^ and lack of centering of the cornea and 
the lens. 

5. Astigmatism of the posterior surface of the cornea. 

6. Contraction of the recti muscles. 

7. Spherical aberration. 

8. Imperfect instruments. 



■i 



350 THE REFRACTIOX OF THE EYE 

1. Faulty observation. — The discrepancy between the read- 
ing of the instrument and the astigmatism as found on subjec- 
tive examination, which is due to faulty observation, of course 
is onl}^ an apparent one ; and a second and more careful ex- 
amination usually clears it up. A poor light or uneven posi- 
tion of the head in the head-rest accounts for many of these 
mistakes in observation. Again, and especially in the aged, or 
in case of cliildren who have been crj^ing, tears standing in the 
eyes often cause an incorrect estimate to be made. In fact, 
sometimes when the astigmatism is with the rule, if of small 
amount, it may appear to be against the rule. This seems to be 
brought about by the tears standing in the groove between the 
lower eyelid and the eyeball and encroaching on the lower half 
of the cornea. The anterior surface of the tears between the 
edge of the eyelid and cornea assume a concave shape, lessen 
the refraction of the cornea in the vertical meridian, and cause 
the instrument to read astigmatism against the rule, when 
there is actually a small amount of astigmatism with the rule. 
Where the astigmatism is of considerable amount and with the 
rule, it would be lessened to some extent by this cause ; and if 
against the rule, increased to some extent. 

That the tears can modify the refractive power of the eye 
there is no question, because, strictly speaking, the tears form 
the first refractive surface of the eye, since there is always a 
thin layer of tears on the front of the cornea to keep it moist. 
But this layer is so thin and in such close contact with the 
cornea, and moreover, having about the same index of refrac- 
tion of the cornea, its influence is so weak that it may, as a rule, 
be neglected entirely (Hirschberg, Ceiitralhl. fur med. Wi%- 
sensch.., 18T4). However, when the tears collect in excess in 
the eye, so as to encroach upon the lower half of the cornea, 
they may materially affect the reading of the ophthalmometer. 

2. Lenticular astigmatism. — Javal, Nordenson, Schiotz, and 
many observers since them, have established the fact that 



LENTICULAR ASTIGMATISM 351 

lenticular astigmatism amounts as a rule to .50 to .75 D. This 
may be called tlie normal astigmatism of the lens, just as we 
have about the same amount of astigmatism normally present 
in the cornea. In fact, the two, as a rule, neutralize each 
other. The lenticular astigmatism may amount to 1 or 1.50 D., 
or even to 2D., and, in rare exceptions, to even more. In a 
case of lenticonus anterior in my practice, reported in this chap- 
ter, it amounted to as much as 7.50 D! But this is a very rare 
case, only five or six cases of lenticonus anterior having been 
reported in all literature thus far. 

Javal 1 has reported a case of lenticular astigmatism of 2D.; 
Carl Weiland,^ a case with similar amount; and George M. 
Black, ^ a lenticular astigmatism of 3.50 D. But all of these 
are exceptional cases. The lenticular astigmatism, as a rule, 
amounts to but .50 to .75 D., as proved by abundant statistics, 
whereby it is shown that, in actual practice, the corneal astig- 
matism is diminished or increased that amount, accordingly as 
the astigmatism is with or against the rule. The most reason- 
able explanation to be given for the necessity of deducting .50 
to .75 D. from the reading of the instrument when the astigma- 
tism is with the rule, and adding a like amount when the astig- 
matism is against the rule, is in the following assumption, to 
wit : That, in corneal astigmatism with the rule, there is usually 
associated a lenticular astigmatism of .50 to .75 D.,in the same 
meridian, but of an opposite kind, thereby neutralizing that 
amount of the corneal astigmatism ; and, in astigmatism against 
the rule, there is usually present a lenticular astigmatism of .50 
to .75 D. in the same meridian and of the same kind, thereby 
adding that amount to the corneal astigmatism.* 

1 3Iemoires d'' Ophtalmometre, p. 121. 

2 Knapp's Archives of Ophthalmology, Vol. XXII, 1893. 

3 Loc. cit., Vol. XXI, 1892. 

* I am aware of the fact that this can be explained in another way, to wit : 
In corneal astigmatism, with the rule, the lenticular astigmatism might be of 
the same kind, but in the meridian at right angles to the corneal astigmatism ; 



352 THE REFRACTION OF THE EYE 

In this place it is interesting to note how regular lenticular 
astigmatism is caused. It may be produced by an oblique 
position of the lens, by a slight displacement of the lens, as 
by sub-luxation, or by unequal curvature of its surfaces, ir- 
regular lenticular astigmatism, together with a large amount 
of regular lenticular astigmatism, may be caused by a marked 
displacement of the lens, so that the edge of the lens lies in 
the pupillary space ; by lenticular opacities, as in beginning 
cataract ; and by lenticonus. We may have also a dynamic 
regular astigmatism produced by an unequal contraction of 
the ciliary muscle (Dobrowlsky, Javal). 

Bonders, in his classical book on refraction, has reported 
two cases of lenticular astigmatism ; one (p. 532) '-'-from con- 
genital eccentricity of the crystalline lens " ; ^ and the other case 
(p. 536) due to an oblique position of the lens, with "no, or 
only slight, lateral displacement of the lens." 

I have had the pleasure of observing one such case under 
especially advantageous circumstances, that is, in a case of 
aniridia. Here, because of the complete absence of the iris, 
the lens could be seen plainly. When the patient first came 
under observation the lens was vertical and not displaced at all, 
but in the course of eighteen months it became luxated upward 
to a slight extent (about 1^ mm.), and the upper edge of the 
lens was tilted backward. By reason of this, while the corneal 
astigmatism remained unchanged, the total astigmatism in the 
eighteen months increased 1.50 D. This case is reported in 
full farther on in this chapter. 

in which case, if the meridian at error in both the cornea and lens were myopic 
in nature, a simple myopia of .60 to .75 D. would be produced. In corneal 
astigmatism against the rule (by this explanation) the lenticular astigmatism 
must be of an opposite kind and in the meridian at right angles to the corneal, if 
the total is to amount to more than the corneal. But I believe the first explana- 
tion more likely to be the true one, and, in fact, actual measurements (Bonders) 
and cases reported show it to be true. See Case CXXXVI in support of it. 
1 In the full report of the case, Bonders stated also that the lens " had an 
oblique position." 



LENTICULAR ASTIGMATISM 353 

Again, lenticular astigmatism may be caused by the surface 
of the lens being unequally curved, just as in the cornea. 
Moreover, the principal meridians of the lens may not coincide 
with the principal meridians of the cornea, but "respecting 
this, however, nothing is with certainty known." ^ And this 
same observer, long ago, made measurements showing that the 
axes of the lenticular astigmatism often did not coincide with 
the axes of the corneal astigmatism. Nevertheless, he came to 
the conclusion, '''-that with a Mgh degree of asymmetry of the 
cornea asymmetry of the crystalline lens exists^ acting in such a 
direction^ that the astigmatism for the whole eye is nearly always 
less than that proceeding from the cornea.^'' '^ 

It is certain that, in almost all cases of astigmatism with 
the rule (and they go to make up the great majority of cases), 
the corneal astigmatism on the subjective examination is les- 
sened from some cause, presumably by a lenticular astigmatism, 
whatever be the relative positions of the principal meridians of 
the cornea and the lens. 

In young subjects, moreover, we may have a regular astig- 
matism (dynamic) of the lens, produced by an unequal contrac- 
tion of the ciliary muscle. Dobrowlsky was the first to point 
this out, and Javal made the same observation later. 

Such astigmatism is shown to exist by paralyzing the 
accommodation with atropine, when a corneal astigmatism, 
or part of it at least, which required no correction before 
paralysis, will accept a cylindrical glass ; thus proving conclu- 
sively that the corneal astigmatism must have been corrected, 
in whole or part, by a lenticular astigmatism, which latter, as 
both Dobrowlsky and Javal state, is most probably due to an 
uneven or irregular contraction of the ciliary muscle. 

Irregidar lenticular astigmatism, together with a large 
amount of regular astigmatism, may be produced by a decided 
luxation of the lens, so that its edge or rim lies across the 

1 Donders, Accommodation and Iiefraction of the Eye. ^ Loc. cit. 



354 THE EEFRACTIOX OF THE EYE 

center of the pupil. Luxation of the lens to such an extent 
not only produces irregular astigmatism, but causes diplopia 
by the half of the lens in the pupil acting as a prism. More- 
over, the refraction of the rays of light is so different in the 
two halves of the pupil that everything is confused to the 
patient. In such cases, it is best, as a rule,' to fit the aphakial 
part of the pupil, ignoring the half with the lens altogether, as- 
the best vision is to be obtained by so doing. Such strong 
glasses blui" the images completely for the part of the pupil 
with the lens in it, and this does away with diplopia, at least 
for the eyes singly, although it may be present when both eyes 
are used together. 

Lenticular opacities, as in beginning cataract, produce 
irregular astigmatism, and often cause diplopia. This is due 
to the different sectors of the lens becoming unequally swollen 
or distorted, and thereby their foci made different, with the 
result that diplopia, or polyopia even for one eye, is often 
caused. Glasses do not improve vision much or any in such 
cases, and it is best to wait till the cataract forms, which as a 
rule quickly follows. There are a certain number of cases of 
diplopia and polyopia even which are not due to lenticular 
opacities, and which are entirely relieved by glasses. Dr. St. 
John Roosa, in his recent book. Defective Eyedglit^ emphasizes 
this point, and reproduces some excellent figures of Dr. G. J. 
Bull's of Paris, by way of illustration. He says : " The double 
vision quite often seen in hj^permetropia, or hypermetropic 
astigmatism, a diplo|)ia which is not constant, may always be 
relieved by a correction of the error of refraction. 

" Dr. G. J. Bull has shown that this so-called double vision 
is often to be described 'as the imperfect superposition of a 
series of faint multiples of the original letter. '^ I believe that 
this is the correct view of quite a number of cases of polyopia 

1 The Macmillan Co. , N. Y. 

2 Trans. Oph. Soc. Unit. King., Vol. XVI, p. 204. 



ANGLE ALPHA 355 

monocularis. It explains the ease witli which such cases are 
treated by correction of the error of refraction. The observer 
who will make himself astigmatic to a considerable degree will, 
in an instant, recognize this doubling of vision, which is the 
result of an uncorrected error of refraction in the eye, and has 
nothing to do with insufficiency of the muscles." 

Lenticonus may be the cause of irregular astigmatism, to- 
gether with a large amount of regular astigmatism, though 
such cases are exceedingly rare. 

3. The position of the glass in front of the eye. — Strictly" 
speaking, the cylinder that corrects the astigmatism, as indi- 
cated by the ophthalmometer, should be worn in contact with 
the cornea. For obvious reasons this cannot be done. Glasses 
must be worn about one-half inch in front of the eyes. In low 
or moderate amounts of astigmatism, when not associated with 
a large amount of spherical error, this moving forward of the 
glasses one-half an inch does not alter the power of the glass 
much ; • but in very high degrees of astigmatism, especially 
when in addition there is a big amount of spherical error, 
pushing the glasses forward one-half inch has a great influence 
on its refractive power. This point has to be taken into con- 
sideration, and a proper reduction in the strength of the 
cylinder to be made on this account (see Chapter X for expla- 
nation) . 

For those who wish to pursue the matter further, I may 
say Weiland has discussed this point at length in Knapp's 
Archives of Ophthalmology^ 1893. 

4. Angle alpha. — This angle, as it is well known, is formed 
by the visual line and optic axis., the visual line usually cutting 
the cornea four or five degrees to the nasal side of the center 
of the cornea, while the optic axis cuts the cornea at its 
center. 

Now, ordinarily, when measuring the eye for astigmatism, 
we do not measure the center or summit of the cornea, but a 



356 THE REFRACTION OF THE EYE 

point on the cornea about 5° to the nasal side of its center, or 
in the point cut by the visual line. This must necessarily be 
so, for we have the patient look directly into the center of the 
tube, and, of course, he directs the visual line to that point. 
To be exact, in measuring the astigmatism of the cornea, we 
should find the angle alpha first in degrees, then have the 
patient look a corresponding number of degrees to the nasal 
side when looking toward the tube of the ophthalmometer, 
when the ce^iter of the cornea would be brought into position 
to be measured. And that the astigmatism for the two points 
may be different at the two points has been shown by Helm- 
holtz, Bonders, Knapp, and others. Knapp, in his earliest 
investigations to determine the shape of the cornea, in one case 
showed that the refractive power of the cornea in one and the 
same meridian at a distance of 1.25 mm. from the center of 
the cornea (about 7°) varied as much as one-third diopter ; 
and since the angle alpha may amount in exceptional instances 
to as much as 12°, it is easy to see how the astigmatism at that 
distance from the center of the cornea might vary from that at 
the center. In fact, where the astigmatism is of high amount 
and the angle alpha large, it can be shown clinically with the 
ophthalmometer that the astigmatism varies for the two points. 
Bonders has shown that the surface of the cornea 15° from the 
center becomes rapidly flatter from that distance on to its 
periphery. When using the ophthalmometer of Javal and 
•Schiotz, we do not measure the whole of the cornea, but only a 
small spot, about 12 to 15° (2.50 to 3 mm.) in diameter, with 
its center at the point on the cornea cut by the visual line. It 
can be readily understood that, if this point is 12° to the nasal 
side of the center of the cornea, the point from which the 
image of one of the mires is reflected, when measuring the 
horizontal meridian, must be still further from the center 
of the cornea. At such a great distance from the center 
of the cornea, the surface is considerably flatter than at 



ANGLE ALPHA 357 

the center, and the error in measurement in such an instance 
would likely be considerable, especially if the astigmatism 
happened to be of high amount. Of course, it is altogether 
exceptional to have an angle alpha of 12°, because, as a matter 
of fact, it rarely amounts to more than 5°, and often not to 
more than 2° or 3°, and may therefore, except in very high 
degrees of astigmatism, be left out of consideration altogether. 
In the higher grades of astigmatism, as after cataract extrac- 
tion, it must be taken into account. 

By means of the disk of Placido on the ophthalmometer, 
with the degrees properly marked on it, the center of the 
cornea is easily measured by having the patient look at 
the circle marked with the corresponding number of degrees 
as the angle alpha — to the nasal side when the angle is posi- 
tive, as it usually is, and to the temporal side when it is nega- 
tive. And this is another reason why the Placido disk should 
not be removed from the instrument of Javal, and replaced 
by a plane black disk, as is now done by some instrument 
makers. 

The lack of centering, or collimation, as it is sometimes 
called, of the refractive media of the eye (cornea and lens) is 
thus seen to be exaggerated by the angle alpha, that is, by the 
visual line not coinciding with the optic axis, but cutting both 
lens and cornea to the nasal side of their centers as a rule, 
though it may coincide with or even be to the temporal side 
of the optic axis on rare occasions. I may say the angle gamma 
also increases the error caused by the angle alpha. The eye 
would be a much more correct optical instrument if the visual 
line coincided with the optic axis. Even then, and after leav- 
ing out of the question axial ametropia, it would not likely be 
a perfect instrument, and that, too, on account of improper 
centering of its refractive surfaces. Helmholtz and Knapp 
both have shown that the summit of the crystalline lens does 
not always lie in the corneal (optic axis in practice) axis, but 



358 THE REFRACTION OF THE EYE 

may be as much as 2° to its temporal side. This, of course^ 
would cause astigmatism. 

The want of proper centering of the cornea and crystalline 
lens, and the angle alpha^ must all be put down as causes of 
discrepancy in the astigmatism found by the ophthalmometer 
and that found by subjective examination. 

5. Astigmatism of the posterior surface of the cornea. — The 
posterior surface of the cornea may be astigmatic, just as the 
anterior surface, rendered so by its principal meridians having 
unequal length of radii of curvature. Tscherning has invented 
an instrument, the ophthalmophakometer, for measuring the 
posterior surface of the cornea, also for measuring the surfaces 
of the lens. This instrument is described by A. Javal in 
Norris and Oliver's System of Diseases of the Eye., Vol. 11^ 
pages 135 and 136. 

By actual measurements, the posterior surface of the cornea 
is shown to have a slightly shorter radius of curvature than the. 
anterior surface. A. Javal, in commenting on the same, says ^ 
" The posterior surface of the cornea is found to diminish in 
curvature from the center toward the peripher}^, as in the case 
of the anterior surface, and in case of corneal asymmetry it 
appears also, as might be expected, to follow tlie asymmetry of 
the anterior surface. As a concave lens of asymmetrical curva- 
ture, the effect of the cornea is to compensate in some degree 
the astigmatism of the anterior corneal surface as measured by 
the ophthalmometer. 

"The maximum compensation due to this cause, so far as 
has been observed, is about 1 D. (as estimated for an eye in 
which the total astigmatism measured about 6 D.)"^ 

6. Contraction of the recti muscles. — In a few cases the recti 
muscles can, by voluntary action, alter the corneal astigmatism. 
I have reported one such case in the Manhattan Eye and Ear 
Hospital Rep>orts., January, 1895, where the patient had a cor- 

1 Loc. cit., p. 137. 



SPHERICAL ABERRATION 359 

neal astigmatism with the rule .50 D. which he could, by vol-^ 
untary action of the recti muscles, increase to 2 D. in the right 
eye, and to 1.50 D. in the left eye. When under a mydriatic 
he could still increase the astigmatism iil the right eye to 1.50 
D., and in the left eye to 1 D. The lids were held from the 
eye so they could have no influence. 

This might be called a dynamic corneal astigmatism, just 
as we may have a dynamic lenticular astigmatism caused by an 
unequal contraction of the ciliary muscle. 

7. Spherical aberration. — In very high degrees of astigma- 
tism, the images of the mires are affected by spherical aber- 
ration, and on this account give too large an amount of 
astigmatism. Leroy and Reid have dwelt upon this point, 
and insist that the proper reduction in the amount of the 
astigmatism, as measured by the ophthalmometer, has to be 
made if it is to accord closely with that found on subjective 
examination. 

8. Imperfect instruments^ either hy reason of had construc- 
tion or poor adjustment. — Sometimes the instruments them- 
selves are at fault in construction or material, and do not 
make correct measurements on that account. For instance, 
because of a faulty adjustment of the bi-refractive prism in 
the telescope, I have seen the image of the mires, after having 
been put accurately in line with the axis of the telescope, that 
is, directly in the line of the crossing of the wires in the tele- 
scope, on rotation of the telescope for the second position, go 
nearly out of the field of the telescope, so that they could 
hardly be seen. 

Again, through lack of adjusting the arc that carries the 
mires in the position that exactly coincides with the line 
of doubling of the bi-refractive prism, I have seen instru- 
ments in which the images of the mires could not be made 
to line at any position whatever. This Avas because of the 
faulty position of the arc in regard to the line of doubliiio' 



360 THE REFKACTION OF THE EYE 

of the prism, which caused a permanent and fixed displace- 
ment of the images of the two mires in relation to each other. 

Again, imperfect material as regards the prisms and the 
lenses at times make it necessary to have entirely new prisms 
and lenses put in to replace the old ones. Moreover, I have 
seen instruments which had very clear images at first (both 
the imported and the domestic), which finally became so weak 
and dim that correct observations could not be made with 
them. 

The above eight causes of error in ophthalmometric exam- 
ination, which are here given to account for the discrepancies 
that are sometimes found to exist between the astigmatism as 
measured by the ophthalmometer and that found on subjective 
examination, together with the exceptional cases herein re- 
ported, emphasize the importance of a subjective examination, 
in all cases, after using the ophthalmometer. Although in the 
great majority of cases the ophthalmometer measures the astig- 
matism to within .50 to .75 D., as to amount, and to within 
5° as to axis, yet there are enough exceptional cases to demand 
a subjective examination in all cases. In doubtful cases we 
must make other objective tests besides those made with the 
ophthalmometer and ophthalmoscope, and, if need be, which 
is seldom indeed, a mydriatic should be used, when retino- 
scopy can be used to advantage. 

(1) Cases showing discrepancies as to the amount of the astig- 
matism. 

Case CXXXIV. Corneal astigmatism^ 2.50 D., icith the rule; 
Total astigmatism^ 1.25 i>., hy subjective examination. — Mrs. 
H. H., aged thirty years, in good health, has worn glasses for 
three or four years, consulted me on September 21, 1896, on 
account of headaches and pains in the eyes, especially after 
using the eyes for close work. 

Ophthalmometer. — Astigmatism with the rale, 2.50 D., axis 
90° + or 180° - in each qjq. 



EXCEPTIONAL CASES 361 

Test cards and trial lenses. — 

R. V. = |§ : 1^ + W. - 1.25 D. cyl., 180°. 
^' ^'=U''U + ^' - 1-25 D. cyl., 180°. 

Reads Jaeger No. 1 from 1 to 15 inches. 

Ophthalmoscope, — Em. at 180° and M. 1.50 D. at 90° in 
each eye. 

A second and a third test did not change the glass, and the 
patient would not accept a stronger cylinder with improve- 
ment in vision. I had this patient under observation for more 
than two years, and when last seen the glasses were satisfactory 
and the patient using the eyes with comfort. 

In this case 1.25 D. had to be deducted from the corneal 
astigmatism as measured by the ophthalmometer, or, what 
amounted to the same thing, the patient would not accept the 
cylinder to correct the astigmatism, as indicated by the instru- 
ment, by 1.25 D. 

Case CXXXV. Corneal astigmatism with the rule, 1 D. 
right and 1.50 D. left eye. Patient will accept no cylindrical 
glass; Antimetropia ; Presbyopia. — December 19, 1898, Mrs. 
K. E. H., aged forty-three years, in robust health, has never 
worn glasses, though she has seen poorly with the right eye 
since a child. She comes now for reading glasses. 

Ophthalmometer. — Astigmatism with the rule, 1 D. 90° -1- 
or 180° - right eye, 1.50 D. 90° + or 180° - left eye. 

Test cards and trial lenses. — 

R V — -^- • -2JL w — 13 D 

^' ^ ' — 200 * 100 ^^ ' ^^ ^' 

L. V. = 1^ : will accept no glass. 

Reads Jaeger No. 1 from 8 to 20 inches, with +1.25 D. 
sphere left eye ; no single binocular vision, the patient using 
the left eye for both the distance and the near point. 

Ophthalmoscope. — M. 13 D., with posterior staphyloma and 
choroidal changes right, Em. left eye. 



362 THE REFRACTION OF THE EYE 

In this case, in the good eye, there was a corneal astig- 
matism of 1.50 D., which was neutralized by a like amount of 
astigmatism within the eyeball, perhaps by a lenticular astig- 
matism of that amount. Be that as it may, the simple spheri- 
cal glasses are perfectly satisfactory, a -f 1.25 D. being ordered 
for each eye. Of course no attempt Avas made to fit the right, 
the glass being used for it merely to balance that in the left, 
the good eye. 

Case CXXXVI. Congenital absence of the iris; Corneal 
astigmatism with the rule^ 1.50 I), right and 2 D. left^ axis 5° 
and 175°, respectively ; Total astigmatism 1. D. each^ witli the 
same axes as the corneal astigmatism; In eightee^i months' time 
the corneal astigmatism did not change^ hut the total increased 
to 2.50 D. in each eye^ axis 180° each^ due to slight luxation 
upivard and tilting backward of the upper edges of the crystalline 
lenses. — I have already reported this case ^ from which the 
account is now in the main taken. Annie M. B., aged six, 
was brought to me by her mother, April 12, 1897, to have 
glasses fitted. The mother states that soon after the birth 
of the child she noticed something peculiar about the eyes. 
As the patient grew up she avoided the bright lights and 
always squinted the eyelids when in the sunlight. The child 
has always enjoyed good health, and, except for the defect in 
the eyes, is sound. Since the birth of this, the first child, the 
mother has been delivered of two other children, sound in 
every respect. Both the father and mother are health}^ and 
without defect, and the mother says this is the first member of 
either her or her husband's family thus afflicted. The father, 
mother, and tAvo 5^ounger children are all slightly hyperme- 
tropic, while the patient has compound mj'-opic astigmatism. 

Examination of the eyes. — The ophthalmometer shows 
astigmatism with the rule, 1.50 D., axis 95°-}- or 5°— right 

1 Post-Graduate^ November, 1898. 



EXCEPTIONAL CASES 363 

«ye; 2. D. 85°+ or 175°- left eye. The ophthalmoscope 
shows complete absence of the iris in each eye, nothing but 
a very narrow pigment-ring at the extreme periphery of the 
cornea being present. Nothing of the ciliary processes can be 
seen either with the ophthalmoscope or by oblique illumination. 
The lenses are clear and circular, except a slight nick in the 
lower edge of the right. The vitreous is clear and the fundus 
normal in each. The fibres of the zonule of Zinn can be seen 
distinctly below and at the sides, but not so plainly above, as 
the lenses are slightly displaced upward. The diameter of 
the lenses can be seen with the ophthalmoscope to become 
distinctly smaller when the patient makes strong efforts at 
accommodation. 

R. y. = 32JL : 1^ w. - 4.50 D. - 1 D. cyl., 5°. 

L. V. = 2V0 • li W. - 5 D. - 1 D. cyl., 175°. 

Reads Jaeger No. 2 at 8 inches with these glasses. 

The above glasses, ground in No. 2 London-smoke glass, to 
keep the excessive light from the eyes, were ordered, and with 
these the patient has pursued her studies at school with com- 
fort for eighteen months. I may say that neither stenopseic 
slit or puncture improved the vision. The tension of the eye 
has remained normal. 

I presented the case before the New York Ophthalmological 
'Society, October 10, 1898. The vision at that date was about 
the same as when the patient first came under observation. The 
corneal astigmatism remains exactly the same, but the total has 
increased considerably (1.50 D. in each eye} by reason of the 
lenses being displaced a little upward and the upper margins 
being tilted slightly backward. The myopia has increased to 
some extent. The patient now accepts — 5 D. — 2.50 D. cyl., 
180° right, and -6 D.- 2.50 D. cyl., 180° left. The lenses 
remain clear, but with a suspicion of faint striie of opacity in 



■ 



364 THE REFRACTION OF THE EYE 

the lower halves. The luxation upward is not more than 1 to 
IJ mm., and not enough to cause diplopia. 

In this case there is no question w^iatever of the increase of 
the total astigmatism being due to the slight luxation upward 
and tilting backward of the upper edge of the crystalline lens. 
The displacement and tilting of the lens could be plainly seen 
by reason of the absence of the iris. The ophthalmometer 
showed absolutely no increase in the corneal astigmatism. 

This case, together with others reported, proves beyond 
question that lenticular astigmatism may be caused by an 
oblique position of the lens. 

(2) Cases showing variation as to the axes of the corneal 
astigmatism and total astigmatism. 

Case CXXXYII. Corneal astigmatism with the rule^ axis 
90°+ or 180°— in each eye; Patient accepts minus eyli^idrical 
glasses, axis 15° right eye, and 30° left eye. — October 12, 1895, 
Mr. C. H. D., aged 28 years, in good health, has worn glasses 
for six or seven years, consults me now because of redness of 
the eyelids and pain in the eyes. 

Ophthalmometer. — Astigmatism with the rule, .75 D., axis 
90°+ or 180°- each eye. 

Test cards and trial lenses. — 

^' V- = 2'A : |t + W. - 3 D. - .50 D. cyl., 15°. 
L. V. = ^Vo : 1^ + W. - 3 D. - .75 D. cyl., 30°. 

Reads Jaeger No. 1 from 5 to 18 inches. 

Ophthalmoscope. — M. 4 D. in each eye. No fundus lesion. 

On a second test the ophthalmometer gave the same reading 
as at first ; however, the patient accepted the glasses as at first, 
that is, 15° and 30°, respectively, distant from the axis as indi- 
cated by the ophthalmometer. The glasses were satisfactory 
as long as the patient was under observation, which was about 
six months. 



EXCEPTIONAL CASES 365 

Case CXXXVIII. Ophthalmometer shows corneal astig- 
matism with the rule^^ 60° + or 150° — left eye; Patient accepts a 
plus cylinder axis 30°, that is^ 30° distant from the point indi- 
cated hy the instrument. — Mrs. L. R., aged fifty years, has worn 
glasses for the last eight years, but none of them have been 
comfortable, and she comes now to see if she cannot get better 
glasses. 

Ophthalmometer. — Astigmatism with the rule, 1 D., axis 
90° + or 180° - right eye ; 1 D., axis 60° + or 150° - left eye. 

Test cards and trial lenses. — 

R. Y. = 1^ : 1^ W. + .75 D. + .50 D. cyl., 90°. 
L. V. = II- : f-o- W. + .75 D. + .50 D. cyl., 30°. 

Reads Jaeger No. 1 from 9 to 20 inches, with + 2 D. sphere 
added. 

Ophthalmoscope. — H. 1.50 D. each. 

Second test : ophthalmometer gave exactly the same read- 
ing as at the first test. 

R. V. = 1^ : 1^ W. + 1.25 D. + .50 D. cyl., 90°. 
L. V. = f-^ : 1^ W. + 1.50 D. -f- .50 D. cyl., 30°. 

This last glass was ordered for distant vision, and + 2 D. 
sphere was added to it for reading. 

(3) Cases with discrepancies both as to the axis and the 
amount of the astigmatism. 

Case CXXXIX. Corneal astigmatism ivith the ride in each 
eye; Total astigmatism is against the ride and at different axis 
from that 'of the corneal astigmatism; Marked asthenopia; Re- 
lieved hy the glasses accepted on subjective examination, which 
glasses were not according to the reading of the ophthalmometer. — 
This case was examined by Dr. Kinney in his private practice, 
and it is through his courtesy that I am able to report it here. 
November 22, 1897, Mrs. S. L. M., aged thirty-eight, consulted 



266 THE REFRACTION OF THE EYE 

Dr. Kinney, complaining of headaches and a strained feeling 
in the eyes Avhen she used them to any extent. She is in fairly 
good health, but is troubled with malaria. 

Ophthalmometer. — Astigmeitism. with the rule, .50 D., axis 
75° + or 165° — right eye ; with the rule, .75 D., axis 105° + or 
15° - left eye. 

Test cards and trial lenses. — 

R. V. = 1^ : -If + W. + .75 D. cyl., 165°. 
L. V. = ff : ff + W. + .50 D. cyl., 165°. 

Reads Jaeger No. 1 from 10 to 20 inches with the distance 
glasses. 

Ophthalmoscope. — Showed hypermetropia of about 1 D. in 
each eye. Normal fundi, and no opacities in the refractive 
media that could be discovered. 

Second and third tests resulted in the patient accepting 
exactly the same glasses as at the first one, and the glasses 
were prescribed. They have been worn with comfort for about 
eighteen months. 

In this case the astigmatism differed considerably in amount, 
.75 D. in each after deducting .50 D. from the reading of the 
instrument for astigmatism with the rule. As to the axis, the 
jprincipal meridians of the cornea and lens (assuming lenticu- 
lar astigmatism against the rule to be the cause of the discrep- 
ancy) coincided in the right ej^e, yet the axis of the cylinder 
had to be worn at right angles to that indicated by the instru- 
ment, because the total astigmatism was against the rule. In 
the left eye the principal meridians of the cornea and lens did 
not coincide, because the cylinder, though worn against the 
rule, did not take the axis at right angles (at 15°) to the astig- 
matism indicated by the ophthalmometer with the rule, but at 
a position 30° distant from that meridian, that is, at 165°. 
Yery likely, as has been proved by actual measurements in 



EXCEPTIONAL CASES 367 

some cases by Donders, this meridian represented a mean 
between the principal meridian of the cornea and lens. 

Case CXL. Corneal astigmatism with the rule^ .50 D.; Pa- 
tient accepts .50 D, cylindrical glass against the rule in each 
eye. — November 20, 1897, Emily S., aged thirty years, has 
worn glasses for three years, came to the clinic of Drs. Lewis 
and Van Fleet, at the Manhattan Eye and Ear Hospital, to 
l^e fitted with glasses. On examination I found the following 
conditions : — 

Ophthalmometer. — Astigmatism with the rule, .50 D., axis 
105° -h or 15° - right eye ; with the rule, .50 D., axis 75° + or 
165° - left eye. 

Test cards and trial lenses. — 

R. Y. = 10 _ . 11 _|_ w. + .50 D. cyl., 15°. 
L. V. = If - : f f + W. 4- .50 D. cyl., 165°. 

Reads Jaeger No. 1 from 5|- to 15 inches. , 

Ophthalmoscope. — H. 1 D. in each eye. 

The patient accepted exactly the same glasses on a second 
test, though the ophthalmometer still showed corneal astigma- 
tism, .50 D., with the rule. A plus .50 D. cyl., 15° right, and 
plus .50 D. cyl., 165° left, were ordered. They proved entirely 
comfortable. 

Here the corneal astigmatism and the internal astigmatism 
had their principal meridians coinciding, but the lenticular 
astigmatism (assuming the internal astigmatism to be in the 
lens) exceeded the corneal astigmatism in amount by .50 D., 
hence reversed the nature of the astigmatism in the total amount, 
and required the cylinders to be worn with their axes exactly 
at right angles to the axes indicated by the ophthalmometer. 

Case CXLI. Large amount of corneal astigmatism against 
the ride^ ivith some irregular astigmatism ; Patient accepted cross 
cylinders not at right angles to each other, the axis of the )ninus 



368 THE REFRACTIOX OF THE EYE 

cylinder being worn 30° and that of the plus cylinder 45° removed 
from the point indicated by the ophthalmometer ; Vision markedly 
improved luith the glasses^ and binocular single vision restored, — 
November 19, 1895, Mrs. Jacob H., aged thirty-seven years, 
in good health, but is of a nervous temperament, consulted 
me on account of a dacryocystitis and for glasses. After the 
dacryocystitis was cured I fitted her with glasses. Previously 
to my fitting her she had worn correction for one eye only, the 
right. 

Ophthalmometer. — Astigmatism with the rule, 1 D., axis 
90^ + or 180° — right eye ; astigmatism against the rule, 8 D., 
axis 30° + or 120° — , with irregular astigmatism, left eye. 

Test cards and trial lenses. — 

L- V. = 2V0 '• U ^^' - 4-50 D. cyl., 90°. 

Reads Jaeger No. 1 from 5 to 16 inches. 

Ophthalmoscope. — R. 1 D. right eye, H. 1.50 D. at 90° 
and M. 5 D. at 180° left eye. The cornea (left) had some- 
what the appearance of a conical cornea, and the shadows 
resembled somewhat those so characteristic of conical cornea ; 
yet, on a side view of the cornea, no particular bulging of that 
membrane could be detected. The radii of curvature by the 
ophthalmometer in the principal meridians were but slightly 
shorter than those of the average cornea. There were no 
opacities of the media in either eye, and the fundus in each 
was normal. 

Second test : the ophthalmometer gave exactly the same 
reading as at first. 

R. V. = f^ : 1^ + W. 4- .75 D. cyl., 90°. 

L. V. = 2V0 • f^ ^^^' - ^-50 D. cyl., 90° + 2 D. cyl., 165°. 

Ad. 12°, ab. 6°, sur. R. and L. 2°. Single binocular vision 
is present, both for the distance and the near point. 



EXCEPTIONAL CASES 369 

A third test corresponded with the second, and the glasses 
were ordered: +.75 D. cyl., 90° right, -4.50 D. cyl., 
90° + 2 D. cyl., 165° left. 

I have kept this patient under observation for more than 
two years, and within a few months I have seen her husband, 
who tells me the glasses are still satisfactory and the patient 
comfortable. 

Perhaps the irregular astigmatism present in this case is 
enough to account for the discrepancy between the reading 
of the instrument and the glasses accepted on the subjective 
examination. 

Case CXLII. Corneal astigmatism with the rule; Patient 
accepts cylindrical glasses against the rule. — November 27, 1897, 
Miss M. S. came to the clinic at the Manhattan Eye and Ear 
Hospital, because of a marked asthenopia and blepharitis margi- 
nalis. She was examined by Dr. Kinney, and by his courtesy I 
was allowed to see the case and report the same here. 

Ophthalmometer. — Astigmatism with the rule, .75 D., axis 
75° 4- or 165°- right eye ; .75 D., axis 105° + or 15°- left eye. 

Test cards and trial lenses. — 

^' "^^ = 1^ = if W. + .50 D. cyl., 15°. 
L- ^' = It : ff W- + -2^ ^' cyl., 105°. 
Reads Jaeger No. 1 from 5 to 20 inches. 
A second test corresponded in every particular with the 
first, most careful examination being made because of the dis- 
crepancy between the reading of the instrument and the astig- 
matism found by the subjective examination in the right eye. 
The glasses were ordered as accepted, and they gave comfort 
and relief from the asthenopia and blepharitis. 

Case CXLIII. Corneal astigmatism against the rule : Total 
astigmatism against the rule, but with the a.ris of the cglinder 15"^ 
from the point indicated hy the instrument, right eye ; No corneal 
astigmatism^ but total astigmatism o/1.25 i>., left eye. — December 



370 THE REFRACTIOX OF THE EYE 

24, 1895, Dr. L. W. H., aged fifty years, in good health, gives a 
history of diplopia affecting the left eye alone (monocular) 
for the last two months. This diplopia is not constant, dis- 
appearing and then recurring for a few days. On the first 
appearance of the trouble in the left eye he had a mild con- 
junctivitis, but that is about well. No history of syphilis, 
rheumatism, or traumatism. On testing the muscles no insuffi- 
ciencies were found. 

Ophthalmometer. — Astigmatism against the rule, .25 D., 
axis 165°+ or 75°— right eye; no corneal astigmatism left 
eye. 

Test cards and trial lenses. — 

R. V. = ff : f ^ W. + .50 D. + .25 D. cyl., 180°. 
L. y. = f^ : f^ W. + 1.25 D. cyl., 30°. 

Reads Jaeger No. 1 from 8 to 24 inches, with + 2 D. sphere 
added for presbyopia. 

QjMhalmoscope. —YL. .50 D. right eye; H. 1 D. at 120° 
and Em. at 30° left eye. No opacities could be detected in 
either lens, although in the left eye there seemed to be a 
wavering or shimmering of the light in looking at the fundus. 
That there was not much the matter with the refractive media 
is shown by the remarkable acute vision of the patient. One 
would naturally suspect a beginning cataract, to account for 
the occasional monocular diplopia, especially at his age, fifty 
3^ears. As the doctor was from a neighboring state I have not 
been permitted to follow up the case. Roosa^ claims that 
functional diplopia is often seen in hypermetropia and hyper- 
metropic astigmatism, that it is not constant, and that it is 
always relieved by a correction of the error of refraction. (See 
full explanation on page 354.) 

I prescribed the reading glasses for the patient, which were 
satisfactory at the time given. 

iRoosa, Defective Eyesight^ The Macmillan Co., N.Y. 



EXCEPTIONAL CASES 371 

Case CXLIY. No corneal astigmatism right eye ; Corneal 
astigmatism against the rule 180° + or 90° — left eye^ hut the 
patient accepts a plus cylinder at 150° instead of 180° as indi- 
cated hy the ophthalmometer; Spasm of accommodation ; Mydri- 
atic used. — November 8, 1898, Mr. G. D., aged eighteen, 
student, consulted me on account of redness and pain in the 
eyes. The patient is in good health, but is a close student, 
and his eyes hurt him most in the evening. On account of 
the conjunctivitis, I gave him an astringent wash and applied 
alum to the lids once a day for a few days before giving him a 
careful test for glasses. 

Ophthalmometer. — No corneal astigmatism right eye ; as- 
tigmatism against the rule, .25 D., axis 180° + or 90° — left 
eye. 

Test cards and trial lenses. — 

R. V. = 1^ - : |o + W. + .25 D. -h .25 D. cyl., 180°. 
L. V. = |-^ - : 1^ + W. + .50 D. cyl., 170°. 

Reads Jaeger No. 1 from 4 to 18 inches. 

Ophthalmoscope. — H. 1 D. each eye. 

On a second test the ophthalmometer gave the same read- 
ing as at first, but the patient would not accept the axis of the 
cylinder as indicated by the instrument (left eye), but at 170° 
as on the first test. On this account, and because of the symp- 
toms of spasm of accommodation, I advised a mydriatic, but 
the patient declined, saying he was willing to make a trial 
of the glasses without a mydriatic being used. I therefore 
ordered them. The glasses gave him comfort for about two 
months, so that he could pursue his studies, but at the end of 
that time he returned, complaining of headaches and pains in 
the eyes. At this time he consented to have a mydriatic used, 
and I paralyzed the accommodation with scopolamine, \ per 
cent, solution, instilled one drop, every five minutes, six con- 
secutive times. 



372 THE REFRACTION OF THE EYE 

Ophthalmometer. — Astigmatism negative right eye ; astig- 
matism against the rule, .25 D. 180° + or 90° — left eye. 
Test cards and trial lenses. — 

R. V. = ^-^^ : 10 w. + 1 D. + .25 D. cyl., 180°. 
L. V. = 32_(L : 1^ w. + 1 D. + .25 D. cyl., 150°. 

Ophthalmoscope. — H. 1 D. each. 

Three days later the patient accepted + .75 D. + .25 D. 
cyl., 180° right, and + .75 D. + .25 D. cyl., 150° left, which 
were ordered. These glasses have given him entire com- 
fort since, though he has used his eyes for long periods at 
a time. 

The cylinder accepted in the left eye had its axis at 150°, 
or 30° distant from the point indicated by the ophthalmometer, 
after a mydriatic was used. 

Case CXLV. — Lenticonus anterior; Corneal astigmatism 
with the rule., 2 D. in each eye ; Total astigmatism is against the 
rule^ 5.50 D. in rights and 4 D. in the left eye ; Vision greatly 
improved with glasses. — December 2, 1895, Mr. J. L. H., aged 
fifty-seven, in good health, a lawyer, consulted me because of a 
severe migraine in the right side of his head, and pain in the 
right eye. Four days previously he had migraine in the right 
side of his head so severely that he was confined to his bed all of 
one day, and has been incapacitated for work ever since. The 
pain seems to radiate from the right side of his head to the 
right eye. He has had such attacks before, but not so badly. 
There is no redness of the eye, nor is there any plus tension, 
or any indication of glaucoma whatever. He has worn glasses 
for fifteen years for reading, with which he got fairly good 
vision. He has never seen very well for distance or near. 
He is now wearing for reading the cross-cylinders : + 2.50 D. 
cyl., 180° -3D. cyl., 90° right eye, and -f 2.50 D. cyl., 180° 
- 1.50 D. cyl., 90° left eye. 



EXCEPTIONAL CASES 



373 



Ophthalmometer. — Astigmatism with the rule, 2 D., axis 
90° + or 180° - right eye ; with the rule, 2 D., axis 75° + or 
165° - left eye. 

Test cards and trial lenses. — 

^' ^' = 2%% '' tVo W. - 2.50 D. - 2.50 D. cyl., 90°. 
L. V. = 2^0= U W. - 1.50 D. - 2.50 D. cyl., 75°. 

Reads Jaeger No. 1 from 7 to 12 inches, with +1 D., — 
2.50 D. cyl., 90° right, and -f- 2 D. - 2.50 D. cyl., 75° left. 

Because of the great discrepancy between the astigmatism, 
as indicated by the instrument, and that found on subjective 
examination, I immediately suspected some trouble with the 
lens, an incipient cataract perhaps. On examination with the 
ophthalmoscope I found no opacity of the lens whatever, but 
to my surprise a transparent protuberance of a conical shape 
on the front surface of the lens of each eye, somewhat like 
that represented in the accompanying diagram. The cornese 
were perfectly clear, except for a very 
minute opacity just to the outer side of 
the center of the left. The shadows re- 
flected from the pupil resembled in a 
marked degree the shadow-crescents seen 
in conical cornea. I could not get a 
double image of the fundus by the direct 
method with the ophthalmoscope, as did 
Webster in his case, the first of this kind 
reported ; however, I did not have the 
pupil dilated as he did, and besides, the 
conicity was not so marked in my case as 
in his, so far as I can judge by reading 
the account of his case and looking at the excellent diagrams 
he gave.i With the indirect method, however, 1 got a 




Fig. 104. — Diagram of 
the crj'^stalliue lens, 
enlarged, giving a 
side view. The front 
of the lens with pvo- 
tnberance on it is to 
the left. 



1 Archives Ophtlial. and Otol, Bd. Vol. IV, 1874-1875, p. 382. 



374 



THE REFRACTIOI^ OF THE EYE 



decided diplopia of the retinal blood-vessels, both vertical 
and horizontal ; also the parallactic movement by which the 
double images could be made to approach toward, or recede 
from, each other by the slightest movement of the ophthalmo- 
scope or object lens. The fundus was normal in each eye. 

On a second test the ophthalmometer gave exactly the same 
reading as at first. 

Test cards and trial lenses. — 



^' ^- = 2V0 : H W. - 5 D. - 2.50 D. cyl., 90°. 
W. - 1 D. - 3 D. cyl., 75°. 



T^ V — 20 . 20 
-^- ^ • — 2 • ST 



Reads Jaeger No. 1, 9 to 15 inches, with — 1 D. — 2.50 D. 
cyl., 90° right, + 3 D. cyl., 165' left eye. These reading 
glasses were prescribed, and have been worn for more than 
three years with comfort ; however, his daughter tells me 
that in the last few months he does not get along so well with 
them as at first. 

This patient, according to the glasses which he was wear- 
ing when he came to me, had a total astigmatism in the right 
eye, 5.50 D., and in the left eye total astigmatism, 4 D., in 
each against the rule. The ophthalmometer, however, gave 
him astigmatism in each eye, 2 D., with the rule. Hence, the 
lens must have had an astigmatism of 7.50 D. in the right, 
and 6 D. in the left, against the rule in each, in order to have 
the total astigmatism amount to 5.50 D. right and 4 D. left,, 
against the rule. According to my own tests when he came to 
me, he must have had a lenticular astigmatism against the 
rule of 4.50 D. right and 5 D. left, in order to have a total 
astigmatism against the rule of 2.5 D. right and 3 D. left, 
because he had 2 D. of corneal astigmatism with the rule in 
each eye. 

The following five cases are given, not because of the dis- 
crepancy in the astigmatism as measured by the ophthalmometer 



EXCEPTIONAL CASES 375 

and that as found on subjective examination, but because they 
are exceptional as regards the general run of cases in refractive 
work. 

Case CXLYI. Corneal astigmatism with the rule .2-5 D.; 
On subjective examination the patient accepted plus .25 D. cylin- 
drical glasses against the rule; In four years'' time the axis of 
the corneal astigmatism and the axis of the total astigmatism^ as 
brought out by subjective examination^ had changed 30°. — Feb- 
ruary 8, 1894, H. D. R., aged thirty-one, in good health, is a 
civil engineer, and uses his eyes very hard in drawing, con- 
sulted me because of pains in the eyes and an occasional 
headache. He had a well-marked conjunctivitis, for which I 
prescribed an astringent wash, and treated a few days before 
testing for glasses. 

Ophthalmometer. — Astigmatism with the rule, .25 D., axis 
75° + or 165° - right eye ; .25 D. axis 105° + or 15° - left eye. 

Te§t cards and trial lenses. — 

R. V. = f^ - : f^ W. + .25 D. cyl., 165°. 
L. y. = 10. _ . 1^ VV. -h .25 D. cyl., 15°. 

Reads Jaeger No. 1 from 4 to 24 inches. 

Ophthalmoscope. — H. .50 D. each. 

A second test ten days later resulted in the patient accept- 
ing exactly the same glasses as at the first test, and they were 
ordered for his close work. 

These glasses gave him relief from asthenopia, and he con- 
tinued to use them for almost five years. For the last year of 
this time his old sjaiiptoms, eye ache and headache, came back 
once in a while. 

December 9, 1898, I saw him again. 

Ophthalmometer. — Astigmatism against the rule, .25 D., 
axis 135° + or 45° — right eye ; with the rule, .25 D., axis 45° 
+ or 135° - left eye. 



376 THE REFRACTIOX OF THE EYE 

Test cards and trial lenses. — 

R. V. =1^ : fl W. 4- .25 D. cyl., 135°. 
L. V. = 1^ : fl W. + .25 D. cyl., 45°. 

Reads Jaeger Xo. 1 from 6 to 20 inches. 

OpJithahnoscojje. — H. .50 D. each. 

Four days later a second test, objective and subjective, cor- 
responded exactly with the previous test, and the glasses were 
ordered. He has worn them for four months with entire relief 
from his asthenopic symptoms. 

In this case, both the corneal and total astigmatism changed 
axes and in the same direction, and to the extent of 30°. 

Case CXLVII. — Corneal astigmatism with the ride., with 
the principal meridians not at right angles. — April 30, 1897, 
Miss N. S., aged twenty-five, in good health, has worn glasses 
off and on for the last ten years, but none of the glasses have 
given her relief from a very troublesome asthenopia. She was 
fitted with glasses twice under the influence of a mydriatic. 

Ophthalmometer. — Astigmatism with the rule, 1 D., the 
images lining at 165° in first position, and at 60° in second 
position, right eye ; .75 D., the images lining at 15° in the first 
position, and at 120° in second position, left eye. 

Test cards and trial lenses. — 

I^- ^- = M • f^ W. + 1.75 D. + .50 D. cyl., 60°. 
L. V. = f^ : 1^ W. + 1.25 D. + .50 D. cyl., 120°. 

Reads Jaeger Xo. 1 from 6 to 20 inches. 

Ojjhthalmoscope. — H. 2.50 D. right eye, H. 2 D. left eye; 
normal fundi, no opacities in the cornese or lenses. 

A second and third test resulted in the patient accepting 
the same glasses exactly as at the first test. The ophthalmom- 
eter gave the same reading in the three tests. The glasses 
were ordered, and gave immediate and continued relief from 



i 



EXCEPTIONAL CASES 377 

the asthenopia. I saw the patient in March, 1899 (two years 
after), v/hen she informed me that she had used her eyes 
constantly as an artist, and that the glasses were still entirely 
satisfactory. 

Case CXLVIII. Corneal astigmatism with the prificipal 
meridians not at right angles in the right eye^ hut at right angles 
in the left eye. — Mrs. J. E. M., aged fifty-eight years, in good 
health, consulted me because her eyes, after using them for 
close work, got a '' sore feeling " in them and became red, 
especially the right one. She has worn glasses for a number 
of years; the last pair, + 2.25 D. spheres, she has worn for eight 
years. 

Ophthalmometer. — Astigmatism with the rule, 1. D., the 
images lining at 180° in first position, and at 75° in the second 
position, right qjq ; .50 D., axis 90° + or 180° — left eye. 

Test cards and trial lenses. — 

R. y. = 1^ - : I J W. - .50 D. cyl., 180°. 
L. V. = 1^ — : not improved with any glass. 

Reads Jaeger No. 1 from 8 to 16 inches, with plus 3 D. 
sphere added. 

Ophthalmoscope. — Em. in each eye apparently. There is 
no opacity of the lenses or the cornese, and fundi are normal. 

The reading glasses were ordered, + 2.50 D. -f .50 D. cyl., 
90° right, and + 3 D. sphere left. These glasses relieved the 
asthenopia, and she no longer complained of the sore and 
strained feeling in the right eye. 

Both in this case and in the one immediately preceding it, 
the cylinders accepted were not at right angles to the meridian 
at error. For instance, in the right eye, in Case CXLYII, the 
cylinder was accepted with its axis at 60°, while the least 
curved meridian was at 165°, as shown by the images lining 
at that point, and, to be worn at right angles, its axis should 
have been at 75° ; while in the left eye the plus cylinder was 



378 THE REFRACTION OF THE EYE 

accepted at 120°, but the least curved meridian, which it was 
given to correct, Avas at 15°. 

And so in tlie present case, in the right eye, the most 
curved meridian was found at 75°, that being the second posi- 
tion and the images overlapping ; nevertheless, the patient 
accepted a minus cylinder, axis 180°, while it should have 
been worn at 165°, to be at right angles to 75°, 

I may say, however, that in some cases, where the principal 
meridians are not at right angles, I have seen the patient 
accept the cylinders with their axes exactly at right angles to 
the meridians at error. So it is well in such cases to try the 
cylinders at both the positions indicated by the ophthalmome- 
ter, and 15°, or at any number of degrees of inclination the 
chief meridians have toward each other from that of a right 
angle. 

Case CXLIX. Large amount of astigmatism^ the corneal 
and total corresponding closely as to amount and exactly as to 
axis ; Patient accepts the glasses as indicated hy the ophthalmome- 
ter with marked improvement in vision^ hut cannot wear any cylin- 
drical correction^ preferring simple spheres. — March 27, 1893, 
Miss K. N., aged thirty-seven years, in good health, came to 
me for glasses. She has worn spherical glasses for close work, 
but not for distance, for ten years. None of them have ever 
been entirely comfortable to the eyes. She complains now of 
occasional headache and pains in the eyes, especially in the 
afternoon and evening. 

Ophthalmometer. — Astigmatism with the rule, 1.25 D., axis 
120° + or 30° - right eye; 5.50 D., axis 80° + or 170° - left 
eye. 

Test cards and trial lenses. — 

R- ^- = M -I^W. + .T5 D. cyL, 120°. 
L. V. = 2V0 : H W. + 4.50 D. cyl., 80°. 
Reads Jaeger No. 1 from 8 to 15 inches. 



■■ 



EXCEPTIONAL CASES 379 

Ophthalmoscope.— Y.m. at 120° and H. 1 D. at 30° right 
€ye; Em. at 75° and H. 5 D. at 165° left. No opacities of 
the cornea or lens in either eye, and no abnormal condition of 
the fundus could be detected in either eye. No muscle insuffi- 
ciency. 

A second test was given, and as the patient accepted the 
same glasses as at first, they were ordered. 

The patient tried faithfully to wear them for two months, 
but claimed they did not help her in the least, in fact, that 
they made the vision worse, because they elongated objects 
very much in the horizontal meridian. A simple +2 D. 
sphere in each eye gave her more comfort than any other 
glasses, and these she continued to wear till her death four 
years later. 

In this case, as well as the one to follow, little or no dis- 
crepancy in the axis and in the amount of the astigmatism, as 
measured by the ophthalmometer and that found on subjective 
examination, existed, nevertheless, the patients were not able 
to wear any cylindrical correction whatever. In seeking an 
explanation of the behavior of the eyes in these two cases, and 
in the others like them, which cases, I may say, are found in 
later life, in presbyopes, as a rule, who have never worn any 
correction in early life, or only a spherical one, though highly 
astigmatic, I can do no better than quote the words of Bonders 
on the action of cylinders in general in the correction of astig- 
matism, and then make a deduction from them in reference to 
the cases here under consideration. He says ; — 

" The correction of regular astigmatism by means of cylindrical glasses 
is incapable of absolute perfection. Apart from the amblyopia, which, inde- 
pendently of the light-refracting system, complicates many cases of astig- 
matism, the acuteness of vision must, even with the most accurate correction, 
leave something to be desired, because the asymmetry of the astigmatic eye 
-cannot be completely counteracted by the presence of a cylindrical lens. 
Moreover, the correction is only of that nature that the posterior focal 
points for tlie different meridians are brought together without the same 



380 THE REFRACTION OF THE EYE 

being true of the other cardinal points. The absolute coincidence of the 
nodal points in the different meridians is scarcely attainable. If they lie in 
the principal meridian of slightest curvature more posteriorly, correction 
with a biconvex cylindrical lens brings them more forward than those in 
the meridian of greatest cm^vature ; and vice versa if they be situated more 
anteriorly, on correction by a biconcave cylindrical lens, they are moved 
more backward. In this is implied that the form of the bodies, on correc- 
tion of astigmatism, is elongated in a direction opposite to that in which, 
before correction, elongation existed," etc.^ 

In other words, in cases of high degrees of astigmatism, 
which have gone without correction till late in life, the subjects 
have become accustomed to images of objects much elongated in 
a certain direction, and when we come to correct the astigmatism 
in these cases we greatly elongate the images in exactly the 
other direction, or the elongation is in the direction at right 
angles to what it was before correction. This is so disturbing 
and so upsetting to all previous ideas of the form and size of 
objects, that some patients simply will not have it, even though 
the vision, so far as test-types are concerned, is greatly im- 
proved by them, as witness the two cases here reported. 
Furthermore, the axes of the astigmatism in both of my cases 
were oblique (and against the rule in one case), and this of 
itself made it much more difficult for them to get used to the 
cylinders ; in fact, they could not, or would not, wear the cylin- 
drical correction. 

Case CL. Corneal astigmatism against the rule, with oblique 
or slanting axis ; Total astigmatism exactly the same as to axis 
and almost identical as to amount; Patient^ vision is greatly 
improved with cylindrical correction, yet he cannot wear it. — 
April 2, 1897, Mr. G. H. W., aged sixty-eight years, in very 
good health considering his years, consulted me for reading 
glasses. He has never worn glasses for the distance, but has 
worn simple spherical glasses for near vision since he was 

1 Loc. cit; p. 509. 



EXCEPTIONAL CASES 381 

forty-five years old, with which he has gotten along fairly well, 
though his vision has always been rather poor. 

Ophthalmometer. — Astigmatism against the rule, 2.50 D., 
axis 5° -I- or 95° — right eye ; against the rule, .50 D., axis 
170° + or 80° - left eye. 

Test cards and trial lenses, — 

I^. V. = 2¥o : l« W. + 2.50 D. cyl., 5^ 

L. V. = iVo : M W. + 1.50 D. + .75 D. cyl., 170°. 

Reads Jaeger No. 1 from 9 to 20 inches, with -}- 4 D. sphere 
added. 

Ophthalmoscope. ^H. 2 D. at 90° and Em. at 180° right 
eye ; H. 2 D. at 90° and H. 1 D. at 180° left; normal fundi; 
no opacities of the refractive media. 

The reading glasses were prescribed, and the patient made 
persistent efforts to use them for six weeks, but finally gave 
them up because of the great disturbance caused by the elon- 
gation of images in' the vertical meridian. With simple 
spherical glasses he got tolerably clear vision for the read- 
ing distance, print appearing natural, if not so distinct as with 
the cylindrical correction ; and he much preferred and was more 
satisfied with the spherical correction. 



I 



APPENDIX 

IMPROVEMENTS ON THE JAVAL-SCHIOTZ OPHTHALMOMETER : 
(a) DAVIS'S DOUBLE-MOVABLE MIRES ; (5) VALK'S GEAR- 
WHEEL ATTACHMENT; (c) SKEEL'S PERPENDICULAR LEVER 
ADJUSTMENT; (d) METAL BASE AND OTHER MINOR IM- 
PROVEMENTS. — REID'S OPHTHALMOMETER, A DESCRIPTION 
OE IT AND HOW TO USE THE INSTRUMENT. — OTHER OPH- 
thalmometers 

Davis's Double-movable Mires for Javal-Schiotz's 
Ophthalmometer ^ 

By the term '^double-movable mires" I mean that both mires, or 
Teflectors (the graduated and rectangular), move at the same time 
and to an equal extent, and not one (graduated), as in the old 
instrument, while the other (rectangular) remains fixed 20° from 
the center of the arc. The advantage of having both mires move 
instead of one is that in so doing both mires are kept the same 
distance from the center of the arc, and their images the same 
distance from any point on the cornea that is being measured; 
whereas, as the old instruments are constructed, one mire (rectan- 
gular) remains fixed at 20° from the center of the arc on one side, 
while the graduated mire on the other side is required to do 
all the moving. This is very well if the point on the cornea hap- 
pens to be of just sufficient radius of curvature in the meridian 
being measured to allow the image of the movable graduated mire 
to just touch the image of the rectangular mire when the graduated 
mire reaches the twenty-degree mark on its respective side of the 
arc. The mires would then be at an equal distance from the center 
of the arc, and their images, consequently, at equal distances from 
the point on the cornea measured. If, however, the meridian 
of the cornea under measurement is of such radius of curvature 

1 Reprinted from the New York Medical Journal, Eebruaiy 10, ISOo. 

383* 



384 THE REFRACTION^ OF THE EYE 

as to allow tlie graduated mire to come closer than. 20° on its 
respective side of the arc before the images of the mires touch, its 
image must necessarily be formed on the surface of the cornea 
nearer the point measured. On the other hand, if the meridian 
under measurement is of such radius of curvature that the images 
of the two mires approximate before the graduated mire reaches the 
twenty-degree mark on its side of the arc, then its image will, of 
course, be formed on the surface of the cornea at a greater distance 
from the point measured than the image from the rectangular mire, 
which is fixed at 20° on the opposite side of the arc. I think 
my point is clear. ISTow, since the human cornea (its apex, or 
point on it where the visual line intersects its surface) is very 
rarely of just the radius of curvature to allow the graduated mire to 
come exactly to 20° on its respective side, — the same distance as 
the fixed mire on the opposite side, — in order to have the images 
touch, any improvement that keeps both mires at the same distance 
from the center of the arc in every case, whatsoever the curvature 
of the cornea may be, is a decided advantage. The double-movable 
mires accomplish this perfectly. 

Those who are only fairly well acquainted with the use of the 
ophthalmometer are aware of the fact that not the whole of the 
cornea is measured in an ordinary ophthalmometric examination, 
but only a very small portion of it — a space only of 2^ to 3 mm. 
in diameter. Furthermore, the center of this space does not 
coincide with the center of the cornea, except when the visual 
line coincides with the long axis of the cornea,^ but with that 
point on the cornea intersected by the visual line, which point is 
usually a little to the nasal side of the center of the cornea, and, 
as a rule, on a horizontal line with it. Or, again, this point may lie 
to the temporal side of the corneal center. The space included 
between this visual line and the optic axis, forward from the point 
where they cross, is the well-known angle alpha, which is positive, 
nil, or negative, accordingly as the visual line lies to the nasal side 
of, coincides with, or is toward the temporal side of the optic axis. 
When the angle alpha is nil or very small, as it is in the majority of 
cases, the center of the small space measured on the cornea practi- 
cally coincides with the center of the cornea, and the measurements 
of the ophthalmometer in such cases, with the proper restrictions, as 
1 Practically the same as the optic axis. 



APPENDIX 385 

laid down by Javal, agree usually with the glasses accepted by the 
patient. When, however, this angle is large, especially when there 
is a large amount of astigmatism associated with a high degree of 
hypermetropia or myopia, the readings of the ophthalmometer do 
not correspond so closely with the subjective test. For example, in 
the natural eye, with a radius of curvature of 8 mm., an angle alpha 
of 6° is 0.9 mm., or, practically, 1 mm. ; and, with an angle alpha 
of 12°, it would, of course, be 2 mm. In such a case, therefore, 
the point on the cornea measured by the ophthalmometer would be 
2 mm. distant from the center of the cornea to the nasal or temporal 
side, accordingly as the angle is positive or negative. Now, the two 
chief radii of curvature at this point may be considerably different 
from the radii of curvature at the apex, — either one or both of 
them. To simplify matters, we will assume that in a given case the 
radius of curvature changes in but one of the chief meridians, — 
that of the vertical, — while it remains unchanged in the horizontal. 
Let the radius of curvature of the horizontal meridian at the apex 
be 8 mm., and that of the vertical meridian 7.61 mm. According to 

Javal's formula, D = 1000 ^^ — — — ^, the astigmatism at the apex in 

r 

such a case is 2 D. Say, however, at 2 mm. distant from the apex 

the radius of the vertical meridian changes from 7.61 mm. to 

7.31 mm., while the radius of curvature of the horizontal meridian 

remains the same as at the apex. According to the same formula, 

D = 1000 ^^~ ^ , the astigmatism at this point would be 4 D. The 
r 

difference in the amount of astigmatism at the two points would 
clearly be 2 D. Of course, this is a much exaggerated case, but it 
serves to illustrate how a large angle alpha may affect the readings 
of the ophthalmometer, and how the astigmatism at the apex of the 
cornea may vary from that at the point on the cornea intersected by 
the visual line. This error holds against the double-movable mires 
as well as the single-movable mire, but not to the same extent, and for 
this reason : Besides having the radii of curvature of the two chief 
meridians differ, which difference represents the amount of astigma- 
tism present, the radius of curvature may be different in one and 
the same meridian and not necessaril}^ have marked irregular astig- 
matism, as in low degrees of conical cornea, or even where there is 
no conical cornea, it being a well-known fact that the farther we go 



386 THE REFRACTIOX OF THE EYE 

toward the periphery of the cornea the flatter its surface becomes. 
This slight change^ of radius of curvature in the same meridian 
may be present in one or both of the two chief meridians of curva- 
ture. Moreover, the difference in the radius of curvature in the 
same meridian is likely to be greater the farther away the second- 
ary point of measurement is made from the primarj'. Herein, in 
fact, lies the advantage of double-movable mires over the single- 
movable mire. With double-movable mires, both images remain the 
same distance from the point on the cornea under measurement, and 
relatively closer to it than in the single-movable mire. Por, as has- 
already been pointed out above, in the instrument with the single- 
movable mire, one mire must remain fixed at 20° from the center of 
the arc, while the other may be nearer to or farther away, accord- 
ingly as the radius of curvature happens to be longer or shorter than 
8.38 mm., the radius of curvature of the cornea (and the only one, by 
the way), which, by Javal's old instrument, allows the movable mire- 
to be exactly the same distance from the center of the arc (20°) as 
the fixed mire is, and the images touch. If shorter than 8.38 mm., 
both images will become smaller, and to a relative extent, if the 
curve is constant ; and the movable mire would have to be displaced 
farther than 20° on the arc in order to have the images just approx- 
imate. If the surface of the cornea, from which this image of this 
relatively too far displaced movable mire is reflected, happens to 
have a radius of curvature (in one and the same meridian) slightly 
shorter than that point on the cornea from which the image of the 
fixed mire is reflected, then the image from the movable mire would 
be actually smaller than that from the fixed mire. Again, if the 
radius of curvature happens to be longer than 8.38 mm., both images 
will be larger, and the movable mire would have to be moved closer 
than 20° in order to have the images touch. Consequently, the 
image from the fixed mire, in this instance, if the surface from 
which it is reflected is shorter in radius of curvature than that from 
which the image of the movable mire is reflected, will be actually 
smaller than that from the movable mire. Conversely to both of 
the above cited cases, and as most often happens, when the radius 

1 When it is remembered that exactness to the fraction of one one-hun- 
dredth of a millimeter in measuring the radius of curvature of the cornea is 
demanded, the importance of noticing even slight changes of curvature in the 
same meridian will he apparent. 



APPENDIX 387 

of curvature of the surface of the cornea, from which the image of 
the relatively too far displaced mire is reflected, is longer than that 
from which the image of the relatively too close mire is reflected, 
the amount of astigmatism, as measured by the single-movable mire, 
is greater than when measured by the double-movable mires. Fur- 
thermore, other things being equal, the farther removed this image 
of the relatively too far displaced mire is from the center under 
measurement, the greater the change in the surface of the cornea is 
likely to be, with, of course, a resultant increase in the error. With 
double-movable mires, this error does not obtain to the same extent 
as with the single; hence the advantage of the former over the 
latter. However, if there was no advantage in this respect, it is a 
plainly desirable thing to have both mires move and be kept at an 
equal distance from the center of the arc, and their images equidis- 
tant from the center on the cornea under measurement. 

In a year's experience with the double-movable mires I have 
found, in astigmatism of a comparatively small amount — from one 
to four diopters, with little or no hyperopia or myopia, and the angle 
alpha nil or very small — that the readings differed but little from 
those of the single-movable mire, the readings with the double-mov- 
able mires most of the time being less than with the single-movable 
mire, about .25 D. to .50 D. less. On the other hand, in astigmatism 
of large amount, especially when associated with a high degree of 
hyperopia or myopia, where the angle alpha is usually large,^ the 
readings have differed more, often as much as .50 D., and sometimes 
as much as 1 D., the double mires usually giving the less amount. 
Furthermore, the subjective tests corresponds closer with the read- 
ings of the double mires than with those of the single-movable 
mire.^ 

In irregular astigmatism the readings with the double-movable 
mires proved much more satisfactory than the readings with the 
single-movable mire. 

The modus operandi of the double-movable mires consists in a 
thumb-screw attached to the arc on the same side as the graduated 
or movable mire, about two inches from the telescope. On the 
attached end of this screw are cogs, into which other cogs on slender 

1 The angle alpha in these cases was measured with caudle and perimeter. 

2 I have used the double-movable mires for five years uo^Y, aud am more 
favorably impressed with them than ever. 



388 



THE REFRACTION OF THE EYE 



shafts extend to each mire play (Fig. 105, A). Thus, by a simple 
turn of the screw, both mires are moved at the same time to an equal 
extent, in or out, and at pleasure. In this way both mires are kept 
the same distance from the center of the arc in every case. 

Having both mires move at one time necessitates the regradua- 
tion of the arc, both for radius of curvature and for diopters.-^ The 

regraduation for the radius of curvature is obtained by the formula : 

7? 7? ^ D T 

: I :: D: -\- ^i —, which reduced is, R = -^ -• In this formula 





^^M} mwww& ^ 



\\\ 



B 
Fig. 105. 



It represents the radius of curvature to be found; 0, the object^ 
which in Javal's instrument is the imaginary line between the inner 
edges of the reflectors or mires ; 7, the size of the corneal image, 
which is constant, and equals 2.95 mm. ; D, the distance of the 
object from the cornea, also a constant quantity, 560 mm. being 
double the focal distance of the objective, Avhich in Javal's instru- 
ment is 280 mm.^ 

1 So far as the diopter marks on the posterior border of tlie arc are con- 
cerned, perhaps it would be as well, or better even, not to regraduate for them, 
but to leave them as they are. Because, by leaving them as they now are, the 
number of diopters corresponding to any radius of curvature is easily obtained 
by simply doubling the number of diopters indicated by the graduated mire. 

2 This is the focal distance given by Dr. Sulzer ; also 2.95 mm. is the size of 
the corneal image given by this writer in his description of Javal's instrument 
{Description de V ophtalmometre Javal et Schiotz, modele 1889, par le Docteur 
Sulzer, de Winterthur). 



APPENDIX 



389 



To obtain the radius of curvature to be marked in millimeters on 
the inner edge of the arc, corresponding with the 20 D. mark on 
the posterior edge of the arc, we have 



R 



2 X 280 X 2.95 



8.38 mm., 



200 - 295 

and so on, as low down as 6 and as high up as 46, respectively, on 
each side of the 20 D. mark, the radius of curvature ranging from 
13 mm. for the 6 D. mark to 5 mm. for the 46 D. mark (105, B). This 
doubles the width of range of the instrument with the single-mov- 
able mire, and is of service in conical cornea or in very high degrees 
of astigmatism often present after cataract extraction. 

To regraduate the posterior edge of the arc for the new diopter 
marks it is only necessary to begin at the 20 D. mark as it now 
stands, and, going each way, divide the diopter spaces into halves, 
giving to each half the same value that the whole space now repre- 
sents, and number them accordingly. For example, where 21 now 
is, 22 should be placed ; where 22 is, 24, and so on ; and on the other 
side of the 20 D. mark, where 19 now is, 18 should be written, and 
where 18 is, 16, and so on (see Fig. 105, B). 

Valk's Gear-wheel Attachment 

Consists simply of a small cogwheel attached to the side of the 
telescope back of the large disk, with the cogs in this small wheel 




Fig. 106. 



390 



THE REFRACTION OF THE EYE 



made to fit into cogs whicli have been placed around the telescope 
(Fig. 106). By this arrangement the telescope can be revolved evenly 
and the arc and pointers moved for very small distances and main- 
tained at any position given them. 

Skeel's Perpexdicular Lever Adjustment 

By means of a lever placed in the posterior foot of the the tripod, 
the upright, together with the whole instrument, can be raised or 
lowered in a perpendicular direction. This is certainly an improve- 
ment to the tilting backward and forward movement given to the 




Fig. 107. 



instrument when the simple screw alone is used, as in the old 
instrument (Fig. 107). 

Other minor improvements on the chin-rest, forehead-rest, rack 
and pinion for the mires, shade, curtains to keep light from the eyes 
of the observer, etc., have been made. The adjustable forehead- 
rest made by Fox and Stendicke, of this city, is of practical 
advantage. 

Drs. Giles and Chapman have made some modifications in the 
instrument so as to make it portable, that is, to be carried in a con- 
venient case. See description of same in Medical Record, July 25, 
1896. 



APPENDIX 391 

Dr. W. S. Dennett, of New York, has made an improvement on 
tlie electric light attachment.^ 

Meyrowitz's solid metal base for the instrument to rest on is 
much preferable to the old wooden base or planchette of the 
imported instrument. 

Accurate measurements without any of the above improvements, 
however, can be made with the 1889 model, simply by taking a little 
more time and care. Those who do not care to go to the expense of 
adding all of the improvements to an already expensive instrument 
can procure the unimproved instrument at a moderate cost. 

Meyrowitz has made a new model of the Javal-Schiotz ophthal- 
mometer. In this model he has left off the large dial of Placido, 
and replaced it with a smaller black dial. At the same time he has 
added a smaller dial at the back of the telescope, by which the axis 
of the astigmatism is read off. 

The advantages claimed for this model are : (1) That the tripod 
supporting the instrument is permanently attached to the base, 
thereby giving it greater steadiness, and is moved forward and back- 
ward by a rack and pinion, while the lateral motion is given by a 
revolving joint at the foot of the tripod; (2) The improvements 
made on the 1889 model of the Javal instrument are retained. 
Among these are the "perpendicular adjustment" of the entire 
instrument (Skeel's), and the "simultaneous movement" or "double- 
movable mires" (Davis's). A new and important improvement to 
this latter movement has been made by the addition of a beveled 
gear attachment which permits the manipulation of the mires from 
the back of the large dial ; and by means of a circular scale with 
double automatic pointers corresponding to the graduations on the 
arc, the relative position of the mires on the arc can be read with 
great accuracy. 

Another new feature is the raising and lowering of the chin-rest 
from the opposite end of the ophthalmometer, by means of a cam 
operated by a long rod and milled head at the end of same, so that 
the operator need not change his position. Below a good cut of the 
instrument is given. 

Another new model of the ophthalmometer is that made by 
Chambers and Inkeep, of Chicago. The special advantages that 

1 iYeto York Eye and Ear Inrirmarn Feports, 1804. II. 27. 



892 



THE REFRACTION OF THE EYE 



they claim are: (1) Stationary luminous mires; (2) Adjustable 
prisms. 

There are still other models of the instrument on the market, 
but, in my opinion, the 1889 model of Javal and Schiotz is as accu- 
rate as any of them. Not only that, but measurements outside of 




Fig. 108. 



the visual line can be made with the 1889 model, because it has the 
large dial of Placido attached, while all of the new model instru- 
ments have replaced it with a plane black disk or dial. 



Artificial Corner 

Some eight or nine years since, Javal made an artificial cornea, 
astigmatic in nature, which could be attached to the chin-rest of the 
instrument, and used for testing the correctness of the ophthal- 



APPENDIX 



393 




Fig. 109. — Javal's Artificial 
Cornea. 



mometer itself. Since the radii of curvature of the principal 
meridians of this artificial cornea are known, and their exact re- 
fractive power in the equivalent diopters, it is easy to tell if an 
instrument is at fault in its measurements. 
The meridian of shortest radius of cur- 
vature represents a refractive power of 
44.2 D., while the meridian of longest ra- 
dius represents a refractive power of 42.5 D. 
The difference between these two numbers 
gives the amount of astigmatism of the 
artificial cornea, 1.7 D., which of course 
is constant. The axis of this astigmatism, 
however, can be changed at will, since the 
cornea is on a movable disk. The merid- 
ian of shortest radius of curvature is indi- 
cated by an arrow. Consequently when the arrow points to 0° 
(directly above on the rim), the astigmatism is with the rule ; and 
when pointed horizontally to 90°, the astigmatism is against the 
rule. All intermediate positions, of course, can be taken. Because 
of the brilliant images which it gives, and the fact that it can be 
looked at for a long while, make it of much practical value to the 

beginner, because he can prac- 
tice on it. 

Morgan's artificial cornea 
has been constructed to be used 
in connection with the Javal 
ophthalmometer. It consists of 
a highly polished glass hemi- 
sphere, ground to the radius of 
a normal cornea, and placed in 
the center of a graduated cell, 
similar to such as are found on 
trial frames. When attached 
to the head-piece of the oph- 
thalmometer, the cornea occu- 
pies the position intended for 
the eye of the patient. In this way the ophthalmometer can readily 
be tested, and adjusted if necessary. For purposes of denu^nstva- 
tion, this normal cornea can, b}^ the insertion of a cylindrical lens 




Fig. 110. — Morsran's Artificial Cornea. 



394 



THE REFRACTION OF THE EYE 



into the revolving cell, be converted into an astigmatic cornea of 
any desired degree, with the axis at any given angle. 



Reid's Ophthalmometer 

The inventor's original description of his instrument is as fol- 
lows : ^ "The object of the instrument about to be described is to 
measure the curvature of the central area of the cornea, the polar 
or optical zone; or of any spherical reflecting surface from 6 to 
10 mm. radius. In its present form the instrument can only be 
applied to the measurement of the corneal surface in the visual line. 
As this is the area of the cornea utilized for distinct vision, this 
instrument furnishes all the data practically requisite for the diag- 
nosis and measurement of corneal astigmatism. 

" The theory of its construction is based on a particular appli- 
cation of the following well-known optical law: That when two 
centered optical systems are so combined that their principal foci 
coincide, the ratio of the size of the object to the size of the image 
formed by the combined systems is equal to the ratio of the princi- 
pal foci of the two optical systems, adjacent respectively to object 
and image. The two optical systems in this case are the convex 
lens of the instrument and the cornea as a reflecting surface, with 
the object in the principal focus of the adjoining optical system. 

" Thus {vide Fig. 1) : — 

" Let MM^ be the convex lens of known surface, A the corneal 
surface, and P' the point where the principal foci coincide. 




"Let SPhe an object situated at the principal focal distance of 
MM', and let XX' be the principal axis of the system. 

" Then a ray SM parallel to the axis will, after refraction, be 

1 From the Annals of Ophthalmology and Otology, April, 1896. 



APPENDIX 395 

directed to the principal focus P' of the curved surface of the cornea, 
and therefore be reflected in the direction IB parallel to the axis 
XX\ IB prolonged will meet the ray directed to the center C at 
the point S'\ therefore, S^ is the image of S, and >S"P' is the image 
of SP, and S^F^ is in the principal focus of the convex reflecting 
surface. 

" In the similar triangles MP'O and IP' A, 

P'O^MO 
P'A lA' ' 

SM and IS\ the prolongation of the reflected ray, are parallel to the 
axis XX', therefore SP = MO and S'P = lA. 

rri. f P'O SP OF 

Therefore = , or — = — 

P'A SF'' I f 

therefore — = — (1) 

I r ^ ^ 

2FxI 



^^Description of the Instrument 

" The essential parts of the instrument are an aplanatic convex 
lens of known focus, a rectangular prism neutralized in its center by 
a smaller prism, one side of the rectangular prism being adjacent to 
the lens, and a circular or other disk being opposite the other side in 
the principal focus of the lens. When the instrument is held in 
front of the convex reflecting surface with the disk turned toward a 
luminous source, a virtual image of the disk will be formed at the 
virtual focus of the convex reflecting surface. This image will only 
be seen distinctly by the emmetropic eye through the neutralized 
portion of the prism when the focus of the lens in front coincides 
with the virtual focus of the convex surface. The ratio of the 
object to the image will be as shown above. If noAv a double-image 
prism be inserted behind the neutralizing prism, which exactly 
doubles this image, its power with the combination is easily deter- 
mined, and therefore the exact size of the image can be measured. 



396 



THE REFRACTION OF THE EYE 



The size of tlie object being known, we have the three elements 
necessary for determining the fourth proportional, the curvature of 
the convex reflecting surface. 

^^The instrument in this simple form presented a number of 
practical difficulties in its manipulation, which were overcome by the 
introduction of a short telescope behind, with double-image prism 
fixed in front of its object-glass. 

^^In its present form the instrument consists of the following 
parts (vide Fig. 2^) : An aplanatic lens Ob, a rectangular prism P 
neutralized in the visual axis by a smaller prism P^, and a telescope, 
with the double-image prism BP fixed in front of the object-glass of 
the telescope OjBI The focal length of the object-glass OB^ is pre- 
cisely the same as that of the aplanatic lens Ob, and cross-wires CW 
at its principal focus are viewed by a Ramsden eye-piece. 




"Before using the instrument it is necessary and sufficient that 
the cross-wires should be distinctly seen at the punctum remotum of 
the observer. The adjusted instrument is held in the observer's 
left hand, which rests on the forehead of the patient, the disk being 
directed to a luminous source to the right of the observer. The point 
of coincidence of the principal foci is found by moving the instru- 
ment to and fro. When the observed eye is directed to the central 
or fixation point and his visual line is vertical to the point of the 
cornea through which it passes, the corneal image doubled and in- 
verted ought to be seen in the center of the field. Instead of using 
circular disks of different dimensions, the size of the image required 
to produce exact contact in any meridian is conveniently and quickly 
obtained by making the required change in the size of a carefully 
coiistructed iris diaphragm. By using a circular object the circular, 



APPENDIX 397 

elliptical, or irregular form of the image reveals at once the con- 
dition of the surface. When the image is elliptical the meridian of 
greatest curvature is easily found by rotation of the telescope, and a 
rotation of 180° gives a controlling observation. By a similar pro- 
cess the meridian of least curvature is determined. 

" Graduation of the Instrument 

"Let D be the power in diopters of the cornea as a refracting 
surface, with a medium behind it of uniform density having an 
index of refraction n = 1.337 approximately. 

jy^ (n- 1)1000 
r 

^337 
r 

" Combining equation (1) with (11), 

337 X O 



(11) 



D = 
D-\-l = 



21F 

337 X 0' 
2IF 



1 = -^ (0' - 0). 
2IF^ ^ 

" In the present instrument 1=2, and 2F= 52, 
therefore 7= 3.24 (0' - 0), 

-^=0'-0: 
3.24 

therefore ID = rather less than i mm. 

"The index is divided into two parts, outer and inner. The 
outer registers the size of the image, and the inner the correspond- 
ing diopters. 

"The degree of refinement with which the measurements may 
be carried out depends entirely on the degree of exactness of deter- 
mination of the constants, especially / and F. I has been determined 
exactly to -^^^ inch, and can be estimated to about y^Vo"- ^^^^ 
focal length of the object-glass can be determined by Cornu's 
method, but in general it is more convenient to measure two-curved 



398 THE REFRACTION OF THE EYE 

surfaces whose radii are exactly known, and within the limits of the 
instrument. 

"The index error is found by taking the number of diopters at 
sufficiently great intervals within the limits of the instrument. In. 
this instrument, if we take the extremes of the index, = 12 mm. 
and = 16 mm., we find the corresponding diopters are 38.9 D. and 
51.84 D. The index being graduated in thirds of a millimeter, the 
index error of each division is nearly 0.08 D., which is positive. 

" If the double prism be now removed, the image being sijigle, 
and the pupillary opening generally distinctly visible, it affords a 
means of determining whether the visual axis passes through the 
center of the pupil. 

" It will be seen that this instrument differs from the ophthal- 
mometer of Helmholtz, the most perfect instrument theoretically 
and practically which has been devised for this purpose, in which, 
while the object is constant, the image varies with the curvature of 
the surface, but always covers the same angular interval of the 
surface. It resembles the ophtlialmometre pratique of Javal and 
Schiotz, in which the doubling is effected by means of a double- 
image prism inserted between two achromatic lenses of equal focus,, 
so that while the image is constant the object is made to vary. 
With this instrument, when the difference of curvature of the prin- 
cipal meridians is considerable, amounting to 3 or 4 D., in order to 
obtain approximately accurate results, it is necessary to insert bi- 
refractive prisms of different powers, giving images of from 1 to 
3 mm. In the present instrument the image of 2 mm. has been 
selected as giving sufficiently accurate results for the most practical 
purposes, measuring with precision, as it does, a difference of refrac- 
tion of half a diopter. For cases outside the limits referred to (6 to 
10 mm.) prisms of suitable powers can be substituted." 

Through the courtesy of Messrs. J. H. & G. W. Hahn, New 
York City, I had the use of a Reid's ophthalmometer in my office 
for about five months' time, and I wish to express my thanks in this 
place to the Messrs. Hahn for their kindness in the matter. 

In that time I had many opportunities to compare it with the 
Javal-Schiotz instrument in testing for astigmatism. 

In astigmatism of low and moderate amount, up to 4 D., I found 
it as accurate as the Javal-Schiotz ophthalmometer, as to amount. 
I must say, however, that it was not so accurate in placing the axis 



APPENDIX 399 

of the astigmatism. Especially was this so in astigmatism against 
the rule. Dr. Murdock, of Baltimore, who is familiar with the 
instrument, praises the instrument highly, in fact, believes it more 
accurate than the Javal-Schiotz instrument, though he found the 
same difficulty in iinding the exact axis in astigmatism against the 
rule that I have spoken of. He says: "Its weak point, in my 
hands, but not in Dr. Eeid's, is the difficulty encountered in deter- 
mining the exact angle of an axis against the rule. The two images 
that one looks, at are circles, and I find it difficult to tell when they 
first separate or when they reach the furthest point of separation."^ 

In high amounts of astigmatism, as in conical cornea and after 
cataract extraction, it was not equal to the Javal-Schiotz instrument 
by any means ; in fact, in the very high amounts of astigmatism, it 
could not measure it even approximately. 

In comparison with the Javal-Schiotz instrument it suffers under 
the further disadvantage of not giving the radius of curvature of 
the cornea in millimeters, as does the former instrument. It is true 
that the radius can be calculated by a simple formula, but in office 
work we do not care to waste time in such calculations. There is 
no question but that it is a handy instrument as a portable ophthal- 
mometer, and is easy to use; but, as a rule, patients who want 
glasses fitted are able to come to the office of the oculist. Besides, 
in America at least, we have a portable Javal-Schiotz ophthalmome- 
ter (Drs. Giles and Chapman's). In conclusion, I may say, the 
cost of the two instruments is about the same. 

Dr. C. A. Oliver, of Philadelphia, has invented an adjustable 
bracket for the Eeid ophthalmometer,^ his description of which is 
here appended : — 

"After several years' trial with the various forms of ophthal- 
mometers (keratometers) and much experimentation with the Eeid 
contrivance (by far the best of them all), I have found that for office 
use I have been able to obtain much better results as regards both 
axis and degree of corneal astigmatism by having the instrument 
mounted upon an adjustable table, which, by the employment of 
four leveling screws and a circular form of spirit-level, can be kept 
absolutely level in all horizontal directions during the examination, 

1 Annals of Ophthalmology and Otology^ April, 1806, p. 324. 

2 Read before the December, 1898, meeting of the Section on Ophthalmok">gy 
of the College of Physicians of Philadelphia. 



400 THE REFRACTION OF THE EYE 

thus insuring a greater degree of certainty of answer in reference to 
axis than when the instrument was held in the hand. 

" The apparatus practically consists of a rigid, vertical, steel rod 
holding a sliding bracket, upon which there is fixed a combined 
leveling table containing the instrument. 

" The ophthalmometer itself is held in position by two angular 
supports that are bolted to the upper table, and is so arranged that 
a mere pressure by the hand will release it from their grasp, thus 
making it portable and allowing it to be used as originally intended. 

" Rising from the circumference of the table there are two fixed 
rods, holding on their upper tips a pair of horizontally placed 
sleeves, through which can be slid a fixation bar that can be bolted 
into any position that may be desired by a few turns of two screw- 
heads that pass through threaded openings in the upper parts of the 
sleeves. The rod that is placed on the registering side of the instru- 
ment contains a large circular area, which is situated just opposite 
to the position of the translucent dial. 

" Situated on the top of the table is a carefully constructed, broad, 
circular level composed of a metallic air-tight chamber, covered by 
glass. In the center of the glass cover is an etched circle of one 
centimeter diameter. This chamber, with the exception of an area 
which is of the same size as that of the etched circle on the glass 
cover, is filled with alcohol, — thus making a bubble of air which, if 
the table be level in every horizontal direction, w^ill be situated 
immediately beneath, and rendered exactly coincident with the 
etched glass area above. At the periphery of the table, between 
the circular spirit-level and the edge of the table, there are four 
fenestrated, threaded heads passing through the entire thickness of 
the table itself. 

" Beneath the upper tilting or instrument and spirit-level holding 
table there is a leveling or fixed table fastened firmly to an upright 
supporting rod. Upon this table four immobile pointed heads are 
situated. 

" Between the two tables, loosely supported on the four pointed 
cones of the lower table, there are four grooved, broadly headed 
leveling screws that pass through the fenestrations in the upper 
table, so that the slightest turn given to any one of them will cause 
the bubble of air in the spirit-level to change its position. 

" In the latest model of instrumentation (not shown in the sketch) 



APPENDIX 



401 



there is a central spiral spring firmly held in an upright position 
between the two tables, by which means the upper table is kept 
securely fixed in whatever position the leveling screws ma}^ have 
placed it. 

" To the ophthalmometer itself there 
has been added (which cannot be seen 
in the sketch) a scale by which the exact 
axis of the meridia of the greatest and 
the least corneal refraction can be im- 
mediately read off. 

" If desired, the instrument and the 
leveling tables may be supported on 
an optometer or phorometer bracket or 
tripod, or they can be screwed to the 
top of a table or clamped to the back 
of a chair, thus making them very light 
and easily transportable. 

"To use the instrument, the verti- 
cal rod is bolted to a window-frame in 
such a way that by a mere turn of the 
bracket either eye may be studied (or 
if so desired the window curtain can be 
drawn and either a source of artificial illumination substituted for 
the daylight, or, as the author prefers, a small adjustable aperture 
in the opaque shade may be opened and the diffuse daylight allowed 
to fall directly upon the disk). 

"The patient being placed in position, and the ophthalmometer 
properly adjusted, the work is proceeded with in the ordinary way." ^ 




Adjustable bracket for the Reid 
ophthalmometer. 



Hardy's Ophthalmometer^ 

"The first ophthalmometer was designed by Helmholtz, in the 
first half of the present century ; but the principle involved therein 
was not reduced to practical utility until 1884, when Doctors Javal 
and Schiotz^ in Paris, designed the present model. The principle 
on which it is based is the 7neasurevient of corneal curves by means of 
reflected images viewed through a telescope. 

^ University Medical Magazine, July, 1899. 
2 Descriptiou taken from Hardy's catalogue. 



402 



THE REFRACTIOX OF THE EYE 



" Images reflected, from curved surfaces vrill vary in size accord- 
ing to the radius of curvature of those surfaces, when the objects 
reflected therefrom are uniform in size and distance. For in- 
stance, a circle 20 cm. in diameter, placed at 28 cm. distance, 
would produce a larger reflected image on a cornea which has 
a long radius of curvature than would be produced on one with a 





:^ 



-N 



Fig. I. 



shorter radius. So that, if it were possible to measure the size of 
the images of the above object reflected from a cornea, the exact 
radius of curvature of that cornea could be calculated. Or, con- 
versely, if an image of a given size, say 3 mm., is reflected from the 
cornea, the curvature of the latter can be calculated from the size of 
the object required to produce 3 mm. at 28 cm. distance. It is evi- 
dent, therefore, that the problem to be solved in constructing an 



APPENDIX 



403 



ophthalmometer has been how to either measure the size of the 
image reflected from the cornea, or to obtain on the cornea an image 
of a fixed size, say 3 mm. in diameter. 

" The device employed accomplished both of these results, and is 
shown in section in Fig. I. ^ 

" It consists of a telescope ' T,' to which are attached arcs car- 
rying sliding targets ' A ' and ' B,' called ' mires.' The telescope 
has a combination of lenses such that a surface, when viewed 
through it, will be exactly in focus when the mires 'A' and ^B^ 
are at 2S cm. distance therefrom. By this means the first element 
is obtained, namely, a fixed distance between the cornea and the 
object to be reflected from it. 

"Between the two objectives of the telescope there is placed a 
bi-refringent prism ^P.' This is a prism which has the property 
of doubling in one plane objects seen through it. For instance, a 
circle viewed through the telescope containing the prism will appear 
doubled. The prism is so adjusted that when the telescope is in 
focus the distance between any two corresponding points of the 
doubled images will be ex- 
actly 3 mm. ; consequently, 
when a cornea is viewed 
through this instrument, it 
is seen doubled, the reflec- 
tion of the mires from the 
cornea also • being doubled, 
and the distance between 
either edge of the two im- 
ages of one of the mires 
. would be exactl}; 3 mm. In 
F'ig. II is shown an enlarged 
view of the cornea, with the 
mires reflected on it, as seen 
through the telescope. 

" Now, if the distance be- 
tween the right-hand edge of 

the primary image of the stepped mire ' A,' and the right-hand edge 
of its secondary image 'A',' is exactly 3 mm., and if the right- 
hand edge of the secondary image ' A" i^ exactly in contact with the 
left-hand edge of the primary image ' B,' of the other mire, it is at 




Fig. II. 



4'j4 



THE KEFRACTIOX OF THE EYE 



once CTident that the distance between tlie inner edges of the two 
mires on the arcs is equal to the size of the object which will give 
on the cornea a reflected image 3 mTn. in diameter. Consequently, 
we have here all the means of calculati::i ureied to give as riie 
radial? cf curvature of the Qpmeal surface. 

• TIt mires are made movable on the arcs, one of them having a 
zi-i z . _: :n cE.' Fig- I i:r ^r \ -zient, so that the Of>er- 
::;:. ~_:^t : zinr fhroTigli zhe teles::^e. c:.ii slide the mires away 
r: 11 :z -.:— : ^. r i. c Tier. Tintil their two central images on the cor- 
- - ^ : : - 7- arcs are graduated on their inner edges 
':^ 1 ; :: r _l ~ji^ : ^ iTi:i:rive power in diopters and quarters of a 
piano lens having rhe same curve as the corneal curve indicated by 
the position of the mires. A scale is also provided on the other 
edge of the arc. giving the zadins of the cornea. But, as the instm- 
niriir is i-ifzj isri ior diagnc^ing astigziarisni. ine lirst scale is 



I 



K 



formed as sii:~n in E:g. TIT: one has a simple 

Tiier. with a sir 5 i strps. arranged in groups, 

niv counted: c-jni having a black line bisecting 

thenu and a black background. 

" On the stepped mire, each 

step represents a diopter, the 

distance between the edge of 

the first step and the line of 

the edges of the small white 

squares represents a diopter, 

and each of the small squares 

and the black space between 

then, represent diopters. 

•• The ares carrying the mires 

being farther away from the 

cornea than the nires themselves, in other words, beiug on a circle 

of longer radius than th n :- — h: :h the mires move, the difference 

in the radius is allowei : : ni h - graduation of the arc. 

"The mathematical principle . : ing the construction of the 
insrmment is, that a given distance c-etween the mires and the cor- 
ner :t 28 cm., and a separatLon of the images by the bi-refringent 
: n. i :' mm., then each 5 mm. of distance between the inner 
c^g^; :i the two mires is equal to 1 D. in a medium having the 




Fig. HL 



J 



APFEXDIX 405 

refractive po^er of a hiunaii cornea. So that tlie size of the steps 
of the mire must be exactly o mm., and the graduation on the arc 
enough farther apart to compensate for its longer radius. 

'•' The numberings of the graduations on the inner edge of the arc, 
therefore, are intended to show the number of half-centimeters" dis- 
tance betAveen the inner edges (•' X ' and ' Y,* Fig. Ill ) of the white 
spaces on the two mires. The two edges above mentioned are set 
on the slide carrying them, so that they are exactly in line with 
the inner edges of the slides. And the graduation on the arcs next 
to the inner edges of the slides, added together, give the readings of 
the instrument. For instance, in Fig. I the inner edge of the mire 
'A' stands at about 22^ on the arc, that of the mire 'B' at 22^ 
on its arc, making about 45 D. together ; and if the corneal reflec- 
tions of the mires placed on the arcs as above have their inner 
edges just ' in contact; as shown in Fig. V (not separated or over- 
lapping, as shown in Figs. VI and VII resx^ectively), then the cur- 




FiG. Y. Fig. Y1. Fig. Vn. 

vature of the corneal surface indicated by the positions of the 
slides on the arcs in that case would be such as to produce a focus 
of 45 D. 

" There is no such thing as a normal curvature for the human cor- 
nea, but from statistics a radius of curvature of 7.829 mm. has been 
settled upon as that of the average cornea. Accordingly, we have 
stamped on the arcs the letter ^A,' to indicate the position of the 
mires for a cornea of average curvature. A smaller distance between 
the slides than that shows a corneal curve of less than the average, 
and, hence, a j^resHm/^tion of hypermetropia. A greater distance 
indicated the reverse of the above, or r presumjytion of myopia. 

••The images of the two mires reflected from the cornea being 
farther apart on a cornea of k"mger curvature, or nearer together on 
one of shorter curvature, it follows that, by moving the mires 
until their images appear in contact (Fig. A"), the curve of the cor- 
nea can be read off on the arc, as stated above, and the difference 



1 



I 



406 THE REFRACTIOX OF THE EYE 

between the curvatures of the same cornea in different meridians 
can be determined in the same way. 

"But the main object of the instrument is not to show the abso- 
lute curvature of the cornea, but differences of curvature in its dif- 
ferent meridians, i.e. astigmatism. Hence, the stepped mire is 
provided, which indicates the amount of astigmatism existing by 
the overlapping or separation of the mires when rotated to the oppo- 
site meridian from that in which they were brought in contact. 

" The angles of the two principal meridians are determined as fol- 
lows : The action of the bi-refringent prism is only in one direction, 
and the line or plane of its action is exactly in the plane of the arc 
carrying the mires. By placing on the mires a black line (' H,' 
Fig. Ill) also exactly in the plane with the arcs and the action of 
the prism, that line will only appear continuous through both 
images when it is reflected from one of the principal meridians. 
"When reflected from any other meridian, the 
mires will appear as in Fig. YIII, with the 
black line broken. 

" The telescope is mounted on a tripod, as 

sho^vn in the cuts, and rests upon the stand 

containing the chin-rest for the patient. It is 

rotatable, allowing the arcs to be set at any 

meridian, their position, and also the meridian 

Fig. VIII. ^^ right angles to it, being shown by the index 

fingers on the graduated disk. 

" The whole instrument can be slid back and forth on the stand, 

so as to focus it on the patient's cornea. 

"The telescope, being provided with the correct combination of 
lenses for that purpose, will show a clear image to an observer 
having normal vision, when the mires are exactly 2S cm. distant 
from the cornea. 

" Any error in the eye of the observer will affect the distance by 
about i mm. to each diopter of such error. That is to say, if the 
oculist using the instrument is myopic 2 D., it would focus with 
the mires at 281 mm. from the patient's cornea, in place of 280 
mm. Hence, the readings of the instrument would be vitiated to an 
amount of about -g-i-g- of a diopter for each diopter of error in the 
eye of the oculist. 

"Doctors Javal and Schiotz corrected this by providing cross- 




APPENDIX 407 

hairs in the tube holding the eye-pieces, so that by focussing it upon 
them the error in the oculist's eye could be compensated. But this 
error is so slight, and it is so utterly impossible to construct an 
instrument in which it would have any practical effect, that we 
regard the cross-hairs as an unnecessary obstruction to the view, 
and therefore omit them. 

"In practical use, the main and most important feature of the 
instrument is its definition. For the object viewed through it is an 
image so small that each step on the stepped mire is less than -^-^ of 
a mm. in diameter reflected from a surface that is often very dull. 
So that the lenses must be of very high grade, and their mounting 
very perfect, to prevent a lack of coincidence in their centering, in 
addition to which the metal work must be rigid and closely fitted. 

" The greatest difficulty met with in the manufacture of ophthal- 
mometers has been that of obtaining perfectly clear quality of 
quartz for the bi-refringent prisms. All the Paris-made instruments 
have this style of prism, with the result that many of them have 
very poor definition. We have, therefore, lately adopted the glass 
beveled slabs, as used in the Utrecht make, with the result of a 
very much better definition than elsewhere obtained. 

^'Directions for Use 

. " From the above description of the construction of the instru- 
ment, the following rules for its use will be easily understood : — 

"Place the patient with chin on the rest, and forehead pressed 
firmly against the top of the head-rest, so as to keep the head per- 
fectly steady. Cover one eye with the eye-cover, and tell the 
patient to look into the end of the tube. 

" Set the two targets at ' A,' on the graduated arcs, and revolve 
the instrument until the arcs are horizontal, and the index fingers 
pointing exactly to 90° and 180° respectively. Sight through the 
slot in the large disk, and slide the instrument on the stand until 
the patient's eye is seen through the center of the slot, and is in 
line with the telescope, the top of the cone being brought into line 
with the bottom of the cornea by turning the pinion in the base. 
(A little practice with the individual instrument will enable its 
owner to sight very accurately, so that on looking through the tele- 
scope the images will be clearly in view.) Then slide the instru- 



I 



408 THE REFRACTION OF THE EYE 

ment till the reflections of tlie images are sharply focussed. They 
will appear double, as is shown in Fig. VIII. The two outer 
images, 'B' and 'A',' should be altogether disregarded, and the 
attention fixed solely on the two central images, 'B" and ^A.' 
The instrument should be moved till the central images are exactly 
in the middle of the field of view, as shown in Fig. Ill, and only 
now tell the patient to open the eye as much as possible, not only in 
order to get a better image, but also to prevent pressure of the lids 
on the globe, which causes often a very considerable degree of astig- 
matism. 

" The next step is to find the principal meridians, which is done 
by revolving the instrument and noting separation of the two 
images. The meridian at which the two images appear nearest 
together is the meridian of greatest refraction, and the meridian at 
which they appear to be farthest separated is the one of the least 
refraction. The exact meridian is determined by finding the point 
at which the horizontal line which bisects the two images is exactly 
continuous, as is shown in Fig. V, instead of broken, as is shown in 
Fig. YIII. Having found one of the meridians exactly, move the 
target along the arc by the rack and pinion till the edges of the 
images are just in contact; then rotate the instrument 90°, and 
the amount of astigmatism can be determined by the amount of 
separation or overlapping of the images, as is shown in Figs. VI and 
VII. The targets in Fig. VII overlap two steps, showing 2 D. of 
astigmatism. Those in Fig. VI show a separation equal to two 
steps, as indicated by the square blocks in the margin of the targets, 
so that in this figure an astigmatism of 2 D. is also represented. 

" Concise Rules 

" When measuring the amount of astigmatism by the overlapping 
of the images : — 

" 1. Focus and find center. 

"2. Find meridian of least refraction, viz., that on which the 
images appear farthest apart. 

" 3. Approximate the images and find exact axis of the meridian. 

"4. Rotate 90°. 

"5. Read off amount of astigmatism by overlapping of the 
images. 



APPENDIX 409 

" 6. Having proceeded according to this rule, the perforated index 
finger will indicate the axis of the greatest curvature, or that for a 
plus cylinder, and the solid index finger ^A' will indicate the axis 
of least curvature, or that for a minus cylinder. (See Fig. XI.) 

" The above is the method used with the French instrument, but 
we have added a new method for determining the amount of 
astigmatism. 

''■ We have attached to one of the racks a supplementary slide 
(' S,' Fig. I) with a set-screw. This slide is on the arc, outside of 
the slide carrying the target. After having found the meridian of 
greatest refraction, according to the above method, this supplemen- 
tary slide should be brought against the slide carrying the target, 
and should be fixed in position by the set-screw. This can easily be 
done without moving the eye from the telescope. Then rotate the 
instrument 90°, when the image will appear to separate, and move 
the target by the rack and pinion till the edges of the two images 
again appear to exactly touch. Then note the angles of the two 
principal meridians, as indicated by the index pointers, and the 
amount of astigmatism can be read off from the graduations on the 
arc. These graduations are made by one-quarter diopters. 

"The supplementary slide being fastened in the first position, 
and the slide carrying the target moved away from it to the second 
position, the number of graduations exposed between the two slides 
represent the number of diopters and quarter diopters of astigmatism. 

" Distance Concise Rules 

^' When using supplementary slide : — 

" 1. Focus and find center. 

"2. Find the meridian of greatest refraction, which is that on 
which the images appear nearest together. 

"3. Approximate the images and find exact axis. 

"4. Bring 'indicating slide' against that carrying the target, 
and fasten in position by the set-screw. 

" 5. Eotate 90°. 

" 6. Approximate the images again. 

" 7. Eead off amount of astigmatism on graduated arc. 

" 8. Having proceeded according to the above rule, the solid index 
finger ' A ' (Fig. XI) will indicate axis of greatest curvature, or that 



410 



THE REFRACTION OF THE EYE 




Fig. XI. 



for plus cylinder, and perforated finger ^B' will indicate axis of 
least curvature, or that for minus cylinder." 

My personal experience with the Hardy instrument extended 

over a period of about two 
months in my clinic at the 
Post-Graduate School of Med- 
icine. I found it a practical 
instrument and one of pre- 
cision. In construction it 
is very similar to Javal's in 
its main features, and any 
one familiar with the use 
of the Javal-Schiotz instru- 
ment can use the Hardy 
instrument. 

With other ophthalmometers, Kagenaar, etc., I have not had 
personal experience. Dr. George J. Bull's opinion of the Kagenaar 
instrument, whose judgment in such matters is of much value, is not 
very favorable, if we are to take his estimate of it as given in a 
recent article in the Ophthalmic Record, Vol. 7, p. 604, on "The 
Utility of the Ophthalmometer." He says : " Some have supposed 
that the rival ophthalmometer of Kagenaar or that of Hardy might 
be looked to with better results. Both ideas are entirely erroneous. 
The ophthalmometer of Kagenaar (and that of Hardy), although an 
instrument of considerable merit, has no real advantage as compared 
with the instrument of Javal, and it has the disadvantage that the 
amount of doubling produced by its prism varies with the distance 
of the patient." 

All things considered, I myself prefer the Javal-Schiotz instru- 
ment to any other, and use it exclusively, except when making com- 
parative tests. 



INDEX OF CASES 



CHAPTER III 

Simple Hypermetropic Astigmatism — Simple Hypermetropia 

Case Page 

I. Corneal astigmatism with the rule, 1 D., axis 90° + or 180° — ; 

Patient accepts + .50 D. cyl., axis 90° 45 

II. Astigmatism with the rule, 4 D., axis 10°, to the temporal side 
of the vertical meridian in each eye ; Patient complains of no 
asthenox^ia, but simply of poor vision ; Accepts 3.5 D. cyl. in 
each eye 47 

HI. Corneal astigmatism with the rule, .50 D., neutralized by lenticu- 
lar astigmatism ; Patient accepts simple plus spherical glass . 48 

IV. Corneal astigmatism with the rule, .25 D., neutralized by the 

lenticular astigmatism ; Patient accepts simple spherical glasses 49' 
V. Corneal astigmatism wdth the rule, .25 D., with no lenticular 

astigmatism .50 

VI. Corneal astigmatism with the rule, .50 D., with no lenticular 

astigmatism 51 

VII. Corneal astigmatism with the rule, 1 D. right eye and .75 D. 

left eye ; No lenticular astigmatism 52 

VIII. Corneal astigmatism with the rule, 1 D., with no lenticular 

astigmatism ; Presbyopia 52 

IX. Hypermetropic astigmatism against the rule, 1 D. right eye, 
.75 D. left eye ; Patient accepts .50 D. more than the instru- 
ment reads 53 

X. Corneal astigmatism against the rule ; The patient accepts only 

.25 D. more than the instrument reads 54 

XI. Ophthalmometer shows corneal astigmatism against the rule, and 

the patient accepts .75 D. more than the instrument reads . 55 
XII. Ophthalmometer shows astigmatism against the rule; The 
patient accepts the reading of the instrument exactly in one 
eye, but .25 D. less than the reading of the instrument in the 
other, though the astigmatism is against the rule ... 55 
411 



412 INDEX OF CASES 

Case Page 

XIII. No corneal astigmatism, but the patient accepts a + .50 D. 

cylindrical glass against the rule, at 180° .... 56 

XIV. No corneal astigmatism; The patient accepts + cylindrical 

glasses against the rule at different axes, 180° and 135° 
respectively 58 

XV. Ophthalmometer shows no corneal astigmatism; Patient 
accepts a + .25 D. cylindrical glass against the rule, axis 
180° in each eye 60 

XVI. Ophthalmometer shows no corneal astigmatism ; The patient 
accepts + .75 D. cylindrical glass against the rule, axis 
180° in each eye 60 

XVII. No corneal and no lenticular astigmatism, a moderate 

amount of latent hypermetropia . . . . . 61 

XVIII. Astigmatism with the rule, .25 D., axis 90° + or 180° -, 
according to the ophthalmometer ; Patient accepts a 
+ .25 D. cylindrical glass, axis 180°, against the rule . 62 

XIX. Corneal astigmatism with the rule, .25 D. ; Patient accepts 
+ .25 cylindi'ical glass against the rule and is relieved 
of a marked asthenopia, with marked improvement in 
vision 62 

XX. Both axes slant 30° to the nasal side of the vertical meridian, 

standing at 60° in the right eye and at 120° in the left eye 67 

XXI. Both of the shorter axes slant 15° to the temporal side of the 
vertical meridian, standing at 105° in the right eye and at 
75° in the left eye " . .68 

XXII. Both axes slant but 5° to the temporal side of the vertical 
meridian, standing at 95° in the right eye and at 85° in 
the left eye 70 

XXIIL Axis vertical or 90° in one eye, and 15° from the vertical in 

the other eye, standing at 75° 71 

XXIV. Both axes slant 15° in the same direction from the vertical 
meridian, to the temporal side in the right and to the 
nasal side in the left, standing in each at 105° ... 72 

XXV. Astigmatism against the rule where the axes of the glasses 
slant relatively the same number of degrees from the 
horizontal meridian, standing at 15° in one eye and at 
165° in the other eye 73 

XXVI. Astigmatism with axes at 45° and 135° 75 



INDEX OF CASES 413 



CHAPTER IV 



Compound Hypermetropic Astigmatism — Spasm of Accommodation 

Case Page 

XXVII. Ophthalmometer shows astigmatism with the rule, 1 D. ; 
Patient accepts compomid plus glasses with relief of 

asthenopia and conjunctivitis 84 

XXVIII. Large amount of astigmatism with the axes slanting 
relatively the same number of degrees from the ver- 
tical meridian, 15° to the nasal side, in each eye; 
Patient accepts a compound plus glass with relief of 

asthenopic symptoms 85 

XXIX. Astigmatism against the rule, 1 D., with the axis 15° from 

the horizontal meridian in each eye; Patient accepts 

compound plus glasses and gets relief from asthenopia 86 

XXX. Small amount of astigmatism associated with a large 

amount of hypermetropia ; Marked asthenopia ; Relief 

with glasses 87 

XXXI. Hypermetropic astigmatism in each eye of equal amount, 
2 D. ; Patient accepts a simple plus cylindrical glass 
in one eye, and a compound plus glass in the other; 

Relief from asthenopia 90 

XXXII. Compound hypermetropic astigmatism against the rule in 
one eye ; Large amount of hypermetropia in the other 
eye ; Marked asthenopia ; Relief with the use of glasses 91 
XXXin. Compound hypermetropic astigmatism with the chief 
meridians of curvature at 45° and 135°; Marked as- 
thenopia ; Relief with glasses 93 

XXXIV. Large amount of compound hypermetropic astigmatism 
with the main meridians at 45° and 135°; Severe 
asthenopia ; Amblyopia ; Relief with glasses . . 96 
XXXV. Astigmatism against the rule in one eye and with the rule 

in the other; Marked asthenopia; Relief with glasses 98 

XXXVI. Ophthalmometer shows no corneal astigmatism ; Patient 
accepts + .25 D. cylindrical glass against the rule in 

addition to a spherical glass 99 

XXXVII. The ophthalmometer shoM^s no corneal astigmatism ; Pa- 
tient accepts + -50 D. cylindrical glass against the rule 100 

XXXVIII. Astigmatism with the rule, .25 D. ; Patient accepts + 50 
D. cylindrical glass against the rule with relief from 
marked asthenopia 102 



1 



414 INDEX OF CASES 

Case Pagk 
XXXIX. Ophthalmometer shows corneal astigmatism with the rule, 
.25 D. ; Patient accepts this amount exactly, indicating 
no lenticular astigmatism whatever .... lOS 
XL. Astigmatism with the rule, .25 D. ; Patient accepts .50 D. 
cylindrical glass against the rule, in combination with 
2 D.s ; Latent hypermetropia of 2 D. left uncorrected ; 
Marked asthenopia ; Kelief with glasses . . . 104 
XLL Astigmatism with the rule, 1.50 D. in the right eye and 
2 D. in the left, with 2 D. hypermetropia; Fitted with 
glasses several times under a mydriatic, with but little 
beneht ; Complete- relief with glasses fitted by the aid 
of the ophthalmometer without any mydriatic . .105 
XLn. Astigmatism of large amount, with moderately large 
amount of latent hypermetropia, which latter was left 
uncorrected ; Complete relief of the asthenopia by cor- 
rection of the astigmatism lOS 

XLin. Compound hypermetropic astigmatism with the rule ; 
Spasm of accommodation ; Amblyopia ; Atropine used, 
and but little difference found between the glasses fitted 
without atropine and those fitted under it . . . 115 

XLIV. Compound hypermetropic astigmatism against the rule; 
Spasm of accommodation ; Mild conjunctivitis ; Hyper- 
sesthesia of the retinae ; Scopolamine used . . . 115 
XLV. Hypermetropia of large amount; Spasm of accommoda- 
tion ; Asthenopia ; Atropine used ; Relief with 3 D. of 
latent hypermetropia left uncorrected .... 117 

XLYI. Simple hypermetropic astigmatism; Spasm of accommo- 
dation; Marked asthenopia; Minus cylindrical glasses 
accepted without atropine and perfect vision obtained ; 
Plus cylindrical glasses accepted under atropine and 
perfect vision 11& 



CHAPTER V 

Simple Myopic Astigmatism — Simple Myopia — Presbyopia 

XL VII. Simple myopic astigmatism with the rule; Blepharitis 
marginalis ; Slight asthenopia ; Relief of blepharitis 
with the use of glasses and local treatment . . . 124 
XL VIII. Simple myopic astigmatism with the rule ; Some amblyo- 
pia ; Relief with glasses 125 



1 

i 



INDEX OF CASES 415 

Case Page 

XLIX. Simple myopic astigmatism with the rule of large amount ; 

Amblyopia, and a mild form of asthenopia . . . 126 

L. No corneal astigmatism ; Patient accepts — .50 D. cylindri- 
cal glasses against the rule ; Relief from asthenopia . . 127 

LI. Simple myopic astigmatism with the rule in the right eye ; 
Lenticular astigmatism against the rule in the left eye, 
the ophthalmometer showing no corneal astigmatism ; 
Asthenopia ; Relief with glasses 128 

LII. Simple myopic astigmatism in one eye, and simple myopia 

in the other ; Asthenopia ; Relief with glasses . . . 129 

Lin. Corneal astigmatism with the rule, .50 D. ; Patient accepts 
sirhple spherical glasses of high power for distance, and 
weaker for reading; The rule for giving two pairs of 
glasses in high degrees of myopia considered . . . 131 

LIV. Myopia of moderate amount in one eye and small amount 
in the other ; Occasional divergent squint ; Asthenopia ; 
Relief of the squint and asthenopia with correcting glasses 136 

LV. Myopic astigmatism of moderate amount; Presbyopia; 
Simple minus cylindrical glasses for the distance, and 
cross-cylindrical glasses for reading 138 

LVI. Simple myopic astigmatism with the rule ; Presbyopia ; 
Minus cylindrical glasses for the distance, and plus cylin- 
drical glasses for the near work 138 

LVII. Simple myopic astigmatism with the rule in one eye and 
against the rule in the other ; Presbyopia ; Minus cylin- 
drical glasses for the distance and plus cylindrical glasses 
for reading 139 

CHAPTER YI 

Compound Myopic Astigmatism — Antimetropia 

LVni. A typical case of compound myopic astigmatism; Slight 

asthenopia ; Vision brought up to perfect, f^, with glasses 119 

LIX. Compound myopic astigmatism, where the myopia is con- 
siderable in amount and the astigmatism small in amount; 
Patient is wearing spherical glasses ; Slight asthenopia, 
with poor vision ; Relief with glasses . . . . . 151 

LX. Compound myopic astigmatism, the myopia being large in 

amount, while the astigmatism is small in amount . . 152 



416 INDEX OF CASES 

Case Page 

LXI. Large amount of myopia with a moderate amount of astig- 
matism with the rule ; Axis of the astigmatism horizontal 
in one eye and off from the horizontal in the other; 
Asthenopia ; Relief with glasses 155 

LXII. Large amount of myopia ; Small amount of astigmatism, but 
marked increase of vision by its correction ; Full correction 
worn with comfort 156 

LXTTT. Compound myopic astigmatism in one eye ; Simple myopia 
of small amount in the other; Scopolamine used as a 
mydriatic 157 

LXIV. Compound myopic astigmatism in one eye; Simple myopic 

astigmatism in the other ; Asthenopia marked ; Presbyopia 159 

LXV. Antimetropia with blepharitis marginalis ; Simple hyper- 
metropic astigmatism in one eye, and simple myopic 
astigmatism in the other, with the rule in each eye . . 165 

LXYI. Antimetropia; Amblyopia to some extent; Simple hyper- 
metropic astigmatism in one eye, and simple myopic 
astigmatism in the other, with the rule in each eye . . 167 

LXVIL Antimetropia ; Asthenopia ; Simple hypermetropic astigma- 
tism in one eye, and compound myopic astigmatism in the 
other, with the rule in each eye 168 

LXVIII. Antimetropia; Compound hypermetropic astigmatism in 
one eye and compound myopic astigmatism in the other, 
against the rule in the myopic eye and with the rule in 
the hypermetropic eye ; Marked asthenopia relieved with 
glasses 169 

LXIX. Antimetropia ; Mixed astigmatism right and compound 
myopic astigmatism left eye ; Head carried to the right 
side ; Asthenopia ; Relief with glasses . . . .171 

LXX. Antimetropia; Simple hypermetropia right eye; Simple 
myopia of large amount with convergent strabismus left 
eye ; Correction of strabismus with glasses without opera- 
tion 173 



CHAPTER Vn 

Mixed Astigmatism 

LXXI. Mixed astigmatism of large amount and with the rule in 
each eye ; Asthenopia ; Relief with glasses 



INDEX OF CASES 417 

Case Page 
LXXII. Mixed astigmatism of large amount, with the rule and 
at off axes ; Marked asthenopia, severe headaches, dizzi- 
ness ; Relief with glasses 184 

LXXIII. Mixed astigmatism with the rule; No amblyopia; Per- 
sistent headaches ; Relief with glasses .... 186 

LXXIY. Mixed astigmatism with the rule in one eye ; Hyperme- 
tropic astigmatism with the rule in the other eye ; 
Asthenopia ; Relief with glasses 187 

LXXV. Mixed astigmatism with the rule right eye; Hyperme- 
tropic astigmatism with the rule left eye ; Marked 
asthenopia; Spasm of accommodation; Atropine in- 
stilled ; Relief with glasses 190 

LXXYI. Mixed astigmatism with the rule left eye; Compound 
hypermetropic astigmatism with the rule right eye; 
Asthenopia; Relief with glasses 192 

LXXYII. Mixed astigmatism with the rule left eye ; Simple myopic 
astigmatism with the rule right eye; Amblyopia; 
Asthenopia ; Relief with glasses 193 

LXXVin. Mixed astigmatism with the rule left eye ; Simple myopic 
astigmatism with the rule right eye; Asthenopia; 
Fitted to glasses without atropine, although the child 
was but eight years old ; Relief with glasses . . . 195 

LXXIX. Mixed astigmatism with the rule right eye; Compound 
myopic astigmatism with the rule left eye; Constant 
pain in the eyes; Relief with glasses .... 196 

LXXX. Mixed astigmatism with the rule in each eye, with the 
axes slanting 5° from the vertical and horizontal meri- 
dians in the same direction in each ; Asthenopia ; Relief 
with glasses . . . 198 

LXXXI. Mixed astigmatism against ■ the rule right eye ; No 
corneal astigmatism left eye, but the patient accepts a 
weak cylinder against the rule ; Patient is very nervous ; 
Marked asthenopia ; Relief with glasses .... '200 

LXXXII. Mixed astigmatism against the rule in each eye ; Spasm 
of accommodation ; Marked asthenopia ; Relief with 
glasses '202 

LXXXIII. Mixed astigmatism of small amount against the rule in 
each eye ; Presbyopia ; Asthenopia ; Blepharitis ; Relief 
of asthenopia and blepharitis with glasses . . . 204 



¥ 



418 INDEX OF CASES 



CHAPTER Yin 
Irregular Astigmatism — Coxical Corxea 

Case Pagb 
LXXXIV. Slight irregular astigmatism due to opacities of the 
cornea ; Regular astigmatism ; Amblyopia ; Astheno- 
pia 211 

LXXXV. Irregular astigmatism associated with a large amount of 
regular astigmatism following perforating ulcer of the 
cornea; Marked decrease both of the irregular and 
regular astigmatism, with attendant increase of vision 

in one year's time 212 

LXXXn. Irregular astigmatism associated with regular astigma- 
tism against the rule right eye ; Regular astigmatism 
against the rule left eye; Asthenopia; Relief with 

glasses 215 

LXXXYII. Irregular astigmatism ui each eye; Large amount of 
regular astigmatism in each eye of the mixed variety ; 
Severe asthenopia ; Vision considerably improved and 
asthenopia relieved with the correcting glasses . . 216 

LXXXVIII. Regular astigmatism with the rule right eye ; Irregular 
astigmatism associated with a large amount of regular 
astigmatism with the rule of a mixed nature left eye; 
Asthenopia 218 

LXXXIX. Marked irregular astigmatism, with a large amount of 
regular astigmatism with the rule right eye ; Regular 
astigmatism against the rule left eye ; Asthenopia only 
to a limited degree 218 

XC. Irregular astigmatism very slight, associated with mixed 
astigmatism of large amount against the rule left eye ; 
Emmetropia right eye 219 

XCI. Irregular astigmatism associated with a large amount of 
regular astigmatism -vsith the rule in each eye ; Anti- 
metropia ; Trichiasis ; Asthenopia ; Relief with opera- 
tion and glasses 220 

XCII. Irregular astigmatism ; Regular astigmatism ; Blephari- 
tis marginalis ; Partial relief with glasses . . . 222 

XCin. Irregular astigmatism associated with compound myopic 
astigmatism against the rule left eye; Compound 
myopic astigmatism against the rule right eye; 
Asthenopia : Relief with glasses 223 



INDEX OF CASES 419 

Case Page 

XCIY. Conical cornea, extreme in the right eye and marked in the 
left; Irregular astigmatism; No improvement with 
glasses in the right, but the vision was brought from ^ 
to If with glasses in the left eye 227 

CHAPTER IX 
Strabismus — Insufficiencies of the Recti Muscles 

XCY. Convergent strabismus left eye ; Simple hypermetropia both 

eyes ; Cure by means of glasses and a mydriatic . . 271 
XCVI. Periodic convergent strabismus right eye ; Simple hyperme- 
tropia each eye ; Cure effected in three months by means 

of glasses alone 273 J 

XCVII. Convergent strabismus right eye ; Compound hypermetropic 
astigmatism both ; Amblyopia both, but more marked in 
the right ; Glasses and one operation necessary for a cure . 275 
XCYIII. Convergent strabismus right eye ; Large amount of com- 
pound hypermetropic astigmatism in each eye, more 
marked in the right eye ; Amblyopia in each ; Cured by 

glasses and one operation 276 

XCIX. Marked convergent strabismus in each eye, more pronounced 
in the right (50° right and 25° left) ; Power of fixation 
lost in the right and in the left motion outward is limited 
also, the patient carrying her head to the left in order 
to see straight ahead; Small amount of hypermetropia; 
Cured by tenotomy of the internal recti muscles, and ad- 
vancement of the right external rectus .... 277 
C. Divergent strabismus right eye ; Antimetropia ; Compound 
myopic astigmatism right and compound hypermetropic 
astigmatism left eye; With glasses the squint was re- 
lieved and single binocular vision obtained for distant 

vision, but not for near 2S0 

CI. Divergent strabismus right eye ; Simple hypermetropic astig- 
matism in both ; Correction of refractive error ; Tenotomy 

right external rectus ; Relief 2S1 

CII. Divergent strabismus right eye ; Myopia of high degree right, 
and moderate degree left ; Glasses ; Tenotomy right exter- 
nal rectus without advancement of the internal rectus ; Cure 2S3 i 
CHI. Convergent strabismus right eye marked, and to a moderate 
degree in the left ; Hypermetropia right, compound hyper- 
metropic astigmatism left eye ; Glasses ; Tenotomy of 
internal rectus of each eye ; Cure 2S-i 



420 



INDEX OF CASES 



Case 

CIV. Divergent strabismus right eye; Myopia of large amount 
each eye ; Correction of myopia with glasses ; Tenotomy of 
right external rectus,* with advancement of right internal 
rectus ; Cure . . . . ' 

Periodic convergent strabismus at the age of forty-one, fol- 
lowing a fixed squint of childhood; Never had glasses or 
operation ; Simple hypermetropia ; Squint is non-comitant, 
though not paralytic ; Binocular single vision for distance, 
but not for near 

Periodic convergent strabismus in childhood recovered from 
at the age of thirty-one without glasses or operation ; Large 
amount of compound hypermetropic astigmatism in each 
eye, with marked amblyopia in the left eye ; Asthenopia ; 
Relief with glasses 

Insufficiency of the internal recti muscles ; simple hyper- 
metropia of small amount ; Asthenopia ; Correction of 
refractive error ; Tonics ; Relief 

CVni. Marked insufficiency of the internal recti; Simple hyper- 
metropia of moderate amount ; Asthenopia ; Correction of 
the refractive error ; Tonics ; Relief 

CIX. Insufficiency of the internal recti muscles; Simple hyper- 
metropic astigmatism; Asthenopia; Correction of the re- 
fractive error ; Relief 

ex. Insufficiency of all the recti muscles ; Relatively, the external 
recti were weaker than the others, as an homonymous di- 
plopia was present at times ; Compound hypermetropic as- 
tigmatism ; Correction of refractive error ; Tonics ; Relief 



cv. 



CVI. 



evil. 



Pasb 



286 



287 



289 



290 



291 



293 



294 



CXI. Insufficiency of all of the recti muscles ; Troublesome homon- 
ymous diplopia ; Compound hypermetropic astigmatism ; 
Asthenopia; Dizziness; Correction of refractive error; 
Tonic given, and less work ordered ; Relief . . . 295 

CXII. Insufficiency of the internal recti ; Simple hypermetropic 
astigmatism; Occasional crossed diplopia; Dizziness; 
Marked asthenopia ; Correction of refractive error and 
tonics without relief; Prisms added to glasses without 
relief, but with the development of divergent squint; 
Operation; Relief 297 

CXIII. Insufficiency of the internal recti muscles ; Occasional diplo- 
pia for the near point ; Hypermetropia of small amount, 
with slight astigmatism in the left eye ; Marked astheno- 



INDEX OF CASES 



421 



Case 



pia; Glasses, tonics, prism exercises, open-air exercises, 
and rest, all fail to relieve; Tenotomy of the right exter- 
nal rectus, followed in two and one-half years with tenotomy 
of the left external rectus, effect a cure . . . ; 



Page 



298 



CXIV. Insufficiency of the internal recti; Asthenopia; Photopho- 
bia; Neuralgia; Emmetropia; Reading glasses ordered; 
Tonics; Improvement in the eyes, but not entire relief 
from asthenopic symptoms 301 

CXY. Insufficiency of the internal recti ; Small amount of hyper- 
metropia; Presbyopia; Asthenopia; Correction for near 
work ; Tonics ; Exercise ; Kelief 302 

CXVI. Insufficiency of the internal recti; Mixed astigmatism in 
one eye, and compound hypermetropic astigmatism in the 
other ; Occasional diplopia at the near point ; Severe head- 
aches ; Has had a number of graduated tenotomies ; Cor- 
rection of refractive error ; Tonics; Relief. . . . 803 

CXVII. Insufficiency of the internal recti; Occasional diplopia; 
Asthenopia; Ilypermetropia and Presbyopia; Reading 
glasses ; Tonics ; Relief 304 

•CXVIII. Insufficiency of the internal recti made w^orse by wearing- 
strong prisms, bases in ; Incapacitated for work on account 
of the great pain in the eyes and head ; Compound myopic 
astigmatism; Mild trachoma; By taking off the prisms 
and giving the proper glasses, the patient got entire relief, 
and was able to resume his professional calling, that of a 
lawyer 305 



CHAPTER X 



Astigmatism after Cataract Extraction 

CXIX. Astigmatism against the rule, 3.50 D., axis ISO"^, two weeks 
after operation ; 1.50 D., axis 180°, six weeks after extrac- 
tion ; Patient accepts 4- 10 D. + .75 D. cyL, 180°, and gets 
II vision, six weeks after operation 

CXX. Astigmatism of large amount, 8.50 D., against the rule, axis 
15°, two weeks after operation ; 7 D., axis ISO"""", seven 
weeks after operation ; fj V. with -f 10 1). -f 5 D. cyl., 
180°, seven weeks after the operation 



328 



422 



INDEX OF CASES 



Case Page 

CXXI. Astigmatism of large amomit, 6 D., against the rule, two 
weeks after operation ; Reduced to 1.50 D., two months 
after operation ; Patient at that time accepted all of the 
astigmatism indicated by the ophthalmometer and got 
f4 vision 329 

CXXII. Astigmatism with the rule, 1.50 D., twelve days after 
operation ; Astigmatism did not change in amount or 
axis ; Patient accepted the full amount of astigmatism 
indicated by the instrument, and obtained |^ V. when 
combined with the proper spherical glass . . . 330 

CXXIII. Astigmatism against the rule, 3 D., three weeks after 
operation ; 1 D., six weeks after operation ; No cylinder 
accepted on the final test 331 

CXXIV. Astigmatism of very large amount, 16 D., against the 
rule, two and one-half weeks after operation ; 4 D., three 
months after operation ; Patient accepts 3.50 D. cylinder 
with proper sphere, and gets |^ V., after three months . 

CXXV. Astigmatism of large amount, 15 D., against the rule, 
three weeks after the operation ; Reduced to 13 D. 
after two months, and only to 12 D. after one year and 
a half, leaving 12 D. astigmatism permanently; Pa- 
tient accepted + 11.50 D. cylinder combined with + 4 D. 
sphere ; Axis of the astigmatism did not change in the 
first two months, but had made a change of '15° when 
seen in eighteen months 



332 



333 



CXXVI. Astigmatism of excessive amount, 20 D., against the rule, 
from incarceration of the iris in the wound during heal- 
ing; Patient accepted 16 D. cy]., without any sphere, 
twenty-six days after extraction 335- 

CXXVII. Astigmatism of very large amount, 22 D., against the rule, 
two weeks after operation ; 5 D., against the rule, five 
months after operation, at which point it remained 
stationary ; Change in axis of 10° during healing . . 337 

CXXVIII. Astigmatism against the rule, 3 D., two and one-half weeks 
after operation ; Astigmatism with the rule, 2 D., three 
months after operation, which remained as such for 
about four years, when the patient was last seen ; 
Ophthalmometer showed no corneal astigmatism what- 
ever before the extraction 338^ 



INDEX OF CASES 



423 



Case Page 

CXXIX. Astigmatism against the rule, 10 D., four weeks after 

operation; Six months after operation, astigmatism 

with the rule, 4.50 D., which four months later (and 

ten months after operation) had diminished to about 

1 D. with the rule 338 

CXXX. Astigmatism with the rule, 4.50 D,, three and one-half 
weeks after operation ; Changed to 1.50 D. against the 
rule, after three years, and remained thus at the end of 
five years from, operation ; Case remarkable also for 
acuteness of vision obtained, f§, and for accommodative 
power after the extraction of the lens .... 339 
CXXXI. Astigmatism with the rule, 3 D., three weeks after opera- 
tion; 1.50 D., against the rule, three months after; 
Accepts + 1 D., cylindrical glass, with sphere for dis- 
tance, but no cylinder for reading 341 

CXXXII. Astigmatism against the rule, with a change in the axis of 
30° within one week's time, due perhaps to stretching 
of the wound from needling, which was performed one 

month after the extraction 341 

CXXXIII. Astigmatism 6 D., axis 45°; Section was made directly 
above for the extraction, but the nasal side of the wound 
(left eye) broke open during a needling on the twelfth 
day ; Ultimate vision |§ 342 



CHAPTER XI 

Exceptional Cases 
(1) Cases showing discrepancies as to the amount of the astigmatism 

CXXXIV. Corneal astigmatism, 2.50 D., with the rule; Total astig- 
matism, 1.25 D., by subjective examination . . . SGO 
CXXXV. Corneal astigmatism with the rule, 1 D. right and 1.50 D. 
left eye. Patient will accept no cylindrical glass; 
Antimetropia ; Presbyopia oGl 

CXXXVI. Congenital absence of the iris ; Corneal astigmatism with 
the rule, 1.50 D. right and 2 D. left, axis 5° and 175°, 
respectively ; Total astigmatism 1 D. each, with the same 
axes as the corneal astigmatism ; In eighteen months' 
time the corneal astigmatism did not change, but the 
total increased to 2.50 D. in each eye, axis 180° each, 
due to slight luxation upward and tilting backward of 
the upper edges of the crystalline lenses . . . 362 



424 



INDEX OF CASES 



(2) Cases showing variation as to the axes of the corneal astigmatism 

and total astigmatism 
Case Page 

CXXXVII. Corneal astigmatism with the rule, axis 90° + or 180° — 
in each eye ; Patient accepts minus cylindrical glasses, 
axis 15° right eye, and 30° left eye ... . 364 

CXXXVIII. Ophthalmometer shows corneal astigmatism with the 
rule, 60° + or 150° — left eye ; Patient accepts a plus 
cylinder axis 30°, that is, 30° distant from the point 
indicated by the instrument 365 



\ 



(3) Cases with discrepancies both as to the axis and the amount of 
the astigmatism 

CXXXIX. Corneal astigmatism with the rule in each eye ; Total 
astigmatism is against the rule and at different axis 
from that of the corneal astigmatism; Marked as- 
thenopia; Relieved by the glasses accepted on sub- 
jective examination, which glasses were not according 
to the reading of the ophthalmometer .... 365 

CXL. Corneal astigmatism with the rule, .50 D. ; Patient 
accepts .50 D. cylindrical glass against the rule in each 
eye 367 

CXLI. Large amount of corneal astigmatism against the rule, 
with some irregular astigmatism ; Patient accepted 
cross cylinders not at right angles to each other, the 
axis of the minus cylinder being worn 30° and that of 
the plus cylinder 45° removed from the point indicated 
by the ophthalmometer ; Vision markedly improved 
with the glasses, and binocular single vision restored . 367 

CXLII. Corneal astigmatism with the rule; Patient accepts 

cylindrical glasses against the rule .... 369 

. CXLIII. Corneal astigmatism against the rule ; Total astigmatism 
against the rule, but with the axis of the cylinder 15° 
from the point indicated by the instrument, right eye ; 
No corneal astigmatism, but total astigmatism of 
1.25 D., left eye 369 

CXLIV. No corneal astigmatism right eye ; Corneal astigmatism 
against the rule 180° + or 90° - left eye, but the 
patient accepts a plus cylinder at 150° instead of 180° 
as indicated by the ophthalmometer ; Spasm of accom- 
modation ; Mydriatic used . . . . . . 371 



INDEX OF CASES 



425 



Case 

CXLV. Lenticonus anterior ; Corneal astigmatism with the rule, 
2 D. in each eye ; Total astigmatism is against the 
rule, 5.50 D. in right, and 4 D. in the left eye ; Vision 
greatly improved with glasses 

CXLVI. Corneal astigmatism with the rule .25 D. ; On subjective 
examination the patient accepted plus .25 D. cylin- 
drical glasses against the rule ; In four years' time the 
axis of the corneal astigmatism and the axis of the 
total astigmatism, as brought out by subjective exam- 
ination, had changed 30° 

Corneal astigmatism with the rule, with the principal 
meridians not at right angles 



Page 



372 



CXLVII. 
CXLVIII. 



Corneal astigmatism with the principal meridians not at 
right angles in the right eye, but at right angles in the 
left eye 

CXLIX. Large amount of astigmatism, the corneal and total cor- 
responding closely as to amount and exactly as to axis ; 
Patient accepts the glasses as indicated by the ophthal- 
mometer with marked improvement in vision, but can- 
not wear any cylindrical correction, preferring simple 
spheres 

CL. Corneal astigmatism against the rule, with oblique or 
slanting axis ; Total astigmatism exactly the same as 
to axis and almost identical as to amount ; Patient's 
vision is greatly improved with cylindrical correction, 
yet he cannot wear it 



375 



376 



377 



378 



380 



GENERAL INDEX 



Abduction, 257, 264. 

Accessory effects of strong myopic 

glasses, 147, 153, 154, 155. 
Accommodation, paresis of, as a cause 
of strabismus, 238, 241. 
spasm of, 109. 
Adduction, 257, 264. 
Adjustment of glasses, 317. 
" Against the rule," its meaning, 23. 
Alternating strabismus, 275. 
Amblyopia, 83, 235. 
Amount or degree of astigmatism, 36 
et seq. 
after cataract extraction, 314, 315. 
Amplitude of convergence, 259. 
Angle aljJha, 242. 

as an accessory cause of strabismus, 

242. 
as a cause of apparent strabismus, 

247. 
as a cause of astigmatism, 355. 
its effect on the readings of the 

ophthalmometer, 250. 
negative, 244. 
nil, 244. 
positive, 243. 
Angle gamma^ as a cause of astigma- 
tism, 357. 
Aniridia, 352, 362. 
Anisometropia, 163. 
Anthnetropia, 147, 163. 
Apparent strabismus, 247. 
Appendix, 383-410. 
Arc, graduated, 3, 8. 
Arlt, Adolph, 278. 
Artificial cornea, Javal's, 392. 

Morgan's, 393. 
-Astigmatism against the rule, 23. 
compound H., 24. 



Astigmatism against the rule, com- 
pound M., 25. 

mixed, 26. 

simple H., 23. 

simple M,, 25. 
Astigmatism with the rule, 19. 

compound H., 21. 

compound M., 22. 

mixed, 23. 

simple H., 21. 

simple M., 21. 
Astigmatism, amount of, 36, 37, 38, 39. 

after cataract extraction, 314, 315. 
Astigmatism, axis of, 36, 37, 38, 39. 

after cataract extraction, 316, 317, 
343, 344. 
Astigmatism, after cataract extraction, 
308. 

corneal, 13 et seq. 

compound hypermetropic, 80. 

compound myopic, 148. 

direct, 20. 

dynamic, 352. 

indirect, 20. 

irregular, 209. 

lenticular, 31, 351. 

lenticular irregular, 353. 

lenticular regular, 352. 

mixed, 175. 

of the posterior surface of the cor- 
nea, 358. 

simple hypermetropic, o6. 

simple myopic, 122, 
Atropine, its use in refraction, 82 ct seq. 
Axial or true myopia, 123. 
Axis of astigmatism, 36, 37, 38, 39. 

after cataract extraction, 316, 317, 
343, 344. 

B 
Bannister, 263, 264, 265. 
Base of the ophthalmometer, 3, 391. 



427 



428 



GENERAL INDEX 



Bi-cylindric lenses, 323. 
Bi-refractive prism (Wallaston's), 5. 
Black, George M., 333, 351. 
Baffon, 238. 

Bull, George J., 40, 326, 410. 
Burnett, S. M., 1, 3, 234. 



Chapman, 390, 399. 
Chief meridians at 45° and 135°, S3. 
Chromatic aberration, 318. 
Claiborne, J. H., 65, 200. 
Coleman, W. E., 255. 
Collimation, 357. 

Compound hypermetropic astigmatism, 
80. 

myopic astigmatism, 148. 
Conical cornea, 209, 225. 
Construction of the ophthalmometer, 

(Javal-Schiotz), 3 et seq. 

(Reid's), 394. 

(Hardy's), 401. 
Contact lenses, 209, 233. 
Contraction of the ciliary muscle, as a 
cause of astigmatism, 352, 353. 

of the recti muscles, as a cause of 
astigmatism, 358. 
Convergence, amplitude of, 259. 
Convergent strabismus, 235 et seq. 
Cornea, conical, 209, 225. 
Cross-threads, 5. 
Curvature myopia, 124. 



D 



Davis's double-movable mires, 383. 
Decentering of lenses, 308, 317. 
Dennett, W. S., 40, 268, 391. 
Deorsumduction, 258, 266. 
De Schweinitz, George, 3. 
Description of the ophthalmometer, 

(Hardy's), 401. 

(Javal-Schiotz) 3, et seq. 

(Reid's), 394. 
Deviation, primary, 271. 
Deviation, secondary, 271. 

by Wallaston bi-refractive prism, 
6, 7. 
Deynard, A. B., 263. 



Diopter, 133, 134. 

Dioptric system of numbering glasses,. 

133, 134. 
"Direct astigmatism," 20. 
Divergent strabismus, 235 et seq. 
Dobrowlsky, 352, 353. 
Dodd, 314, 336. 
Donders, 38, 141, 235, 236, 237, 238, 

239, 241, 242, 243, 245, 248, 322, 

352, 353, 356, 367, 379. 
Duane, 240, 265. 

E 

Effect of the recti muscles on the cur- 
vature of the cornea, 275. 
Ely, E. T., 254. 

Emerson, J. B., 254, 327, 331, 332. 
Equilibrium test of the muscles, 259. 



False or spasmodic myopia, 123. 

Faulty observation, as a cause of error 
in the readings of the ophthal- 
mometer, 350. 

Foster, M. L., 83. 

Fuchs, 253, 271, 278. 



G 



General considerations in the use of the- 

ophthalmometer, 36. 
Giles, J. E., 390, 399. 
Glasses, contact, 209, 233. 

hyperbolic, 209, 232, 233. 

periscopic, 309, 326. 

toric, 309, 323. 
Graduated arc, the, 3, 8. 
Graefe, Alfred, 255. 
Graefe, Von, 255, 257, 259. 
Green, John, 3, 78, 319, 323, 325, 326.. 
Guide-lines, 9. 



H 



Hamer, 243, 248. 

Harkness, William, 318, 319. 

Harlan, G C, 255, 325, 326. 

Helmholtz, 1, 226, 356, 357, 398, 401. 

Hirchberg, 40, 350. 

History of the ophthalmometer, 1 et seq.' 



GENERAL INDEX 



429 



Holden, W. A., 317, 321, 322. 

Holt, 255. 

Homatropine, 80. 

Hyperbolic lenses, 209, 232, 233. 

Hypermetropia, 36. 

as a cause of convergent strabismus, 
237. 
Hypermetropic astigmatism, compound, 
80 ; simple, 36. 

against the rule, compound, 24. 

against the rule, simple, 23. 

as a cause of convergent strabis- 
mus, 239. 

with the rule, compound, 21. 

with the rule, simple, 21. 



I 



Illumination of lines, 78, 79. 
Imperfect instruments, as a cause of 

faulty observations, 359. 
Improvements on the ophthalmometer, 

383. 
Incongruous strabismus, 247. 
Index of cases, 411-425. 
Indicator, long, 10. 

short, 10. 
Indirect astigmatism, 20. 
Insufficiencies of the ocular muscles, 

235, 255. 



Javal, 19, 49, 209, 238, 251, 253, 255, 
311, 312, 313, 314, 348, 350, 351, 
392, 398, 399, 401, 406, 410. 
Javal, A., Jr., 38, 39, 358. 
Javal-Schiotz ophthalmometer, 1 et seq. 

construction of, 3. 

history of, 1. 

improvements on, 383. 

modifications of, 391. 

principle of application, 13. 

rules for its use, 16. 
Johnson, W. B., 253. 



K 



Kinney, C. W., 365, 369. 

Knapp, H., 200, 255, 257, 356, 357. 

KoUer, K., 3. 



Landolt, 134, 259, 262. 
Latent strabismus, 256. 
Laurence, 270. 
Lenses, see Glasses. 
Lenticonus, as a cause of astigmatism, 
355. 

report of a case, 372. 
Lenticular astigmatism, 350 et seq. 

irregular, 352, 353, 354, 355. 

regular, 352, 353. 
Lewis, F. N., 40, 327, 338, 339. 



M 



Methods of testing the ocular muscles, 

258 et seq. 
Mires, 3, 9. 
Mixed astigmatism, 175. 

against the rule, 26. 

with the rule, 23. 

transposition of glasses in, 181, 183, 
206. 
Miiller, 238, 247. 
Murdock, 399. 

Mydriatics, their use, 40 et seq. 
Myopia, 122 et seq. 

after cataract extraction, 345. 

as a cause of divergent strabismus, 
240. 

axial or true, 123. 

curvature, 124. 

false or spasmodic, 123. 

in high degrees, 132. 

malignant or progressive, 135, 149. 

rules for giving glasses, 134. 

when presbyopia is present, 140. 
Myopic astigmatism, compound, 148 ; 
simple, 122. 

against the rule, compound, 25. 

against the rule, simple, 25. 

with the rule, compound, 22. 

with the rule, simple, 21. 

N 

Nelson, J. E., 279. 
Nordenson, 350. 
Norris, 3. 
Noyes, H. D., 3, 257, 265. 



430 



GENERAL INDEX 



k 



O 

Objective, 5. 
Oliver, C. A., 399. 

Ophthalmometer (Javal-Schiotz), 1 et 
seq. 

(Chambers and Inkeep's), 391. 

(Hardy's), 401 et seq. 

history of, 1. 

improvements on, 383. 

its construction, 3. 

(Kagenaar's), 410. 

Meyro^Yitz's model of, 391. 

prmciple of application, 13. 

(Reid's), 394 et seq. 

rules for its use, 16. 
Ophthalmophakometer, 358. 
Overlapping of the mires, its cause, 27. 



Payne, S. ^l., 257. 

Percival, 345. 

Periscopic lenses, 309, 325, 326. 

Pfingst, E. 0., 314, 315, 316, .335. 

Placido, 21, 209, 211, 229, 357, 391, 392. 

Planchette, 3. 

Polyopia monocularis, 355. 

Pomeroy, O. D., 327, 330, 341. 

Pooley, T. E., 83. 

Position of the glasses in front of the 

eyes, its influence, 335. 
Presbyopia, transposition of glasses 
when myopia is present, 159 et seq. 
Presbyopic glasses for myopes, 140. 
Primary deviation, 271. 

position, 17. 
Principal meridians at 45° and 135°, 33. 
Principle of the application of the 

ophthalmometer, 13. 
Prisms, bi-refractive (Wallaston), 5. 

their use in testing the ocular mus- 
cles, 257 et seq. 
Progressive myopia, 135, 149. 

glasses for, 153, 155. 

hygienic treatment of, 155. 

R 

Eadius of curvature of the cornea, 37. 
Raehlmann, 232, 233. 
Eeflector, 3. 



Eeid, 210, 226, 312, 313, 359, 399. 

Eeid's ophthalmometer, 394. 

Retinoscopy, 58. 

Eeute, 238. 

Eing, F. W., 3. 

Eisley, S. D., 255, 263, 264. 

Eoosa, St. John, 3, 40, 238, 239, 254, 
255, 256, 263, 327, 335. 

Eoutine examination of the eyes, 41 
et seq. 

Eules for the use of the ophthalmome- 
ter, 16. 

S 

Schiotz, 38, 39, 209, 313, 350, 398, 399, 

401, 406. 
Scopolamine, 82. 
Secondary deviation, 271. 

position, 18. 
Separation of the mires, its cause, 27. 
Simi3le hypermetropia, 36. 

hypermetropic astigmatism, 36. 
Skeel's perpendicular lever adjustment, 

390. 
Skiascopy, 58. 
Smith, ^Y. H., 83. 
Snellen, 200, 340. 
Spasm of accommodation, 109. 
Spasmodic mj'opia, 123. 
Speakman, 3. 
Spherical aberration. 319. 

as a cause of error in the readings 
of the ophthalmometer, 359. 
Starr, M. A., 264. 
Stevens, George T., 257, 259, 263. 
Strabismus, 235. 

alternating, 275. 

apparent, 247. 

convergent, 235 et seq. 

divergent, 235 et seq. 

incongruus, 247. 

latent, 256. 
Strabometer, 270. 
Sulzer, 388. 
Sursumduction, 258, 266. 



Telescope of the ophthalmometer, 3. 

Tenon, 282. 

Tilting of lenses, 319 et seq. 



GENERAL INDEX 



431 



Toric lenses, 309, 323. 
Transposition of glasses, in myopia, 
142, 143, 144. 
in myopes who have become pres- 
byopic, 159. 
of glasses, in mixed astigmatism, 
181, 183, 206. 
Tropometer, 257. 
True or axial myopia, 123. 

V 

Valk, Francis, 3, 37, 39, 389. 
Yalk's gear wheel attachment, 389. 
Van Eleet, Frank, 3, 62. 
Variation in position of the principal 

meridians of curvature of the 

cornea, 65. 



W 

Wallaston's bi-refractive prism, 5. 

Webster, David, 133, 327, 341, 342. 

Wecker, 210. 

Weiland, C, 3, 311, 312, 351, 355. 

Why the mires overlap, 27. 
separate, 27. 

Why we deduct 50 D. from the read- 
ing of the ophthalmometer in 
astigmatism with the rule, 29. 

Why we add 50 D. to the reading of the 
ophthalmometer when the astig- 
matism is against the rule, 29. 

" With the rule," its meaning, 19. 

Woodward, 3. 

Wtirdeman, 3. 



i 



DEFECTIVE EYESIGHT 

The Principles of its Relief by Glasses 

BY 

D. B. ST. JOHN ROOSA, M.D., LL.D. 

Professor Evieritus of Diseases of the Eye and Ear, Post- Graduate Medical 

School and Hospital ; Stirgeoti to the Manhattan Eye and Ear Hospital 

etc., etc. ; Author of " A Clinical Manual of Diseases of the Eye " ; 

^'Ophthalmic and Otic Memoranda" ; "A Practical Treatise 

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with defective eyesight. It is accompanied by many excellent illustra- 
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" It is written in the terse style of the distinguished author, and al- 
though it is an interesting book for the layman to read, it is also a hand- 
book quite complete enough to be a guide to the general practitioner, 
and even to the specialist in ophthalmology." 

— Medical Revieiu of Reviews. 

" It appeals to the ophthalmic practitioner, but also to the general 
physician who wants to familiarize himself with the diagnosis and man- 
agement of the errors of refraction, especially the proper selection of 
spectacles." — Af-ch. of Ophthalmology. 



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HANDBOOK OF OPTICS 

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STUDENTS OF OPHTHALMOLOGY 



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WILLIAM NORWOOD SUTER, B.A., M.D. 

Professor of Ophthalmology, Natio7ial University, and Assistant Surgeon 
Episcopal Eye, Ear, and Throat Hospital, Washington, D.C, 



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L 



CONTENTS 

Introduction. 

CHAPTER 

I. Refraction at Plane Surfaces. 

II. Refraction at Spherical Surfaces. 

III. Refraction through Lenses. 

IV. The Eye as an Optical System. 

V. The Determination of the Cardinal Points of the Eye in Combination 
with a Lens. 
VI. Errors of Refraction-lenses used as Spectacles. 
VII. The Effect of Spherical Lenses upon the Size of Retinal Images. 
VIII. Cylindrical Lenses. 
IX. The Twisting Property of Cylindrical Lenses. 
X. The Sphero-cylindrical Equivalence of Bicyhndrical Lenses. 
XI. Oblique Refraction through Lenses. 
XII. The Effect of Prismatic Glasses upon Retinal Images. 

XIII. The Reflexion of Light. 

XIV. The Optical Principles of Ophthalmometry and of Ophthalmoscopy. 
Appendices. 

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